rtpproxy Module

Maxim Sobolev

   Sippy Software, Inc.

Juha Heinanen

   TuTPro, Inc.

Edited by

Maxim Sobolev

Edited by

Bogdan-Andrei Iancu

Edited by

Juha Heinanen

Edited by

Sas Ovidiu

Edited by

Carsten Bock

   ng-voice GmbH

   Copyright  2003-2008 Sippy Software, Inc.

   Copyright  2005 Voice Sistem SRL

   Copyright  2009-2012 TuTPro Inc.

   Copyright  2010 VoIPEmbedded Inc.
     _________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Multiple RTPProxy usage
        3. Dependencies

              3.1. Kamailio Modules
              3.2. External Libraries or Applications

        4. Parameters

              4.1. rtpproxy_sock (string)
              4.2. rtpproxy_disable_tout (integer)
              4.3. rtpproxy_tout (integer)
              4.4. rtpproxy_retr (integer)
              4.5. nortpproxy_str (string)
              4.6. timeout_socket (string)
              4.7. ice_candidate_priority_avp (string)
              4.8. extra_id_pv (string)
              4.9. db_url (string)
              4.10. table_name (string)
              4.11. rtp_inst_pvar (string)

        5. Functions

              5.1. set_rtp_proxy_set(setid) 
              5.2. rtpproxy_offer([flags [, ip_address]]) 
              5.3. rtpproxy_answer([flags [, ip_address]]) 
              5.4. rtpproxy_destroy([flags]) 
              5.5. unforce_rtp_proxy() 
              5.6. rtpproxy_manage([flags [, ip_address]]) 
              5.7. rtpproxy_stream2uac(prompt_name, count), 
              5.8. rtpproxy_stream2uas(prompt_name, count) 
              5.9. rtpproxy_stop_stream2uac(), 
              5.10. start_recording() 
              5.11. rtpproxy_stop_stream2uas(prompt_name, count) 

        6. Exported Pseudo Variables

              6.1. $rtpstat

        7. MI Commands

              7.1. nh_enable_rtpp
              7.2. nh_show_rtpp

   2. Frequently Asked Questions

   List of Examples

   1.1. Set rtpproxy_sock parameter
   1.2. Set rtpproxy_disable_tout parameter
   1.3. Set rtpproxy_tout parameter
   1.4. Set rtpproxy_retr parameter
   1.5. Set nortpproxy_str parameter
   1.6. Set timeout_socket parameter
   1.7. Set ice_candidate_priority_avp parameter
   1.8. Set extra_id_pv parameter
   1.9. Set db_url parameter
   1.10. Set table_name parameter
   1.11. Set rtp_inst_pvar parameter
   1.12. rtp_inst_pvar usage
   1.13. set_rtp_proxy_set usage
   1.14. rtpproxy_offer usage
   1.15. rtpproxy_answer usage
   1.16. rtpproxy_destroy usage
   1.17. rtpproxy_manage usage
   1.18. rtpproxy_stream2xxx usage
   1.19. start_recording usage
   1.20. $rtpstat-Usage
   1.21. nh_enable_rtpp usage
   1.22. nh_show_rtpp usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Multiple RTPProxy usage
   3. Dependencies

        3.1. Kamailio Modules
        3.2. External Libraries or Applications

   4. Parameters

        4.1. rtpproxy_sock (string)
        4.2. rtpproxy_disable_tout (integer)
        4.3. rtpproxy_tout (integer)
        4.4. rtpproxy_retr (integer)
        4.5. nortpproxy_str (string)
        4.6. timeout_socket (string)
        4.7. ice_candidate_priority_avp (string)
        4.8. extra_id_pv (string)
        4.9. db_url (string)
        4.10. table_name (string)
        4.11. rtp_inst_pvar (string)

   5. Functions

        5.1. set_rtp_proxy_set(setid) 
        5.2. rtpproxy_offer([flags [, ip_address]]) 
        5.3. rtpproxy_answer([flags [, ip_address]]) 
        5.4. rtpproxy_destroy([flags]) 
        5.5. unforce_rtp_proxy() 
        5.6. rtpproxy_manage([flags [, ip_address]]) 
        5.7. rtpproxy_stream2uac(prompt_name, count), 
        5.8. rtpproxy_stream2uas(prompt_name, count) 
        5.9. rtpproxy_stop_stream2uac(), 
        5.10. start_recording() 
        5.11. rtpproxy_stop_stream2uas(prompt_name, count) 

   6. Exported Pseudo Variables

        6.1. $rtpstat

   7. MI Commands

        7.1. nh_enable_rtpp
        7.2. nh_show_rtpp

1. Overview

   This  is  a  module  that  enables  media streams to be proxied via an
   rtpproxy.  Rtpproxies know to work with this module are Sippy RTPproxy
   http://www.rtpproxy.org and ngcp-rtpproxy-ng
   http://deb.sipwise.com/spce/2.6/pool/main/n/ngcp-mediaproxy-ng.   Some
   features  of  the  rtpproxy  module  apply  only  to  one  of  the two
   rtpproxies.

2. Multiple RTPProxy usage

   The    rtpproxy   module   can   support   multiple   rtpproxies   for
   balancing/distribution and control/selection purposes.

   The   module   allows   definition  of  several  sets  of  rtpproxies.
   Load-balancing  will  be  performed  over  a set and the admin has the
   ability to choose what set should be used. The set is selected via its
   id  -  the id being defined with the set. Refer to the "rtpproxy_sock"
   module parameter definition for syntax description.

   The  balancing  inside a set is done automatically by the module based
   on the weight of each rtpproxy from the set.

   The   selection   of   the   set  is  done  from  script  prior  using
   unforce_rtp_proxy(), rtpproxy_offer() or rtpproxy_answer() functions -
   see the set_rtp_proxy_set() function.

   For  backward  compatibility reasons, a set with no id take by default
   the id 0. Also if no set is explicitly set before unforce_rtp_proxy(),
   rtpproxy_offer() or rtpproxy_answer() the 0 id set will be used.

   IMPORTANT:  if  you  use multiple sets, take care and use the same set
   for both rtpproxy_offer()/rtpproxy_answer() and unforce_rtpproxy()!!

3. Dependencies

   3.1. Kamailio Modules
   3.2. External Libraries or Applications

3.1. Kamailio Modules

   The following modules must be loaded before this module:
     * tm module - (optional) if you want to have rtpproxy_manage() fully
       functional

3.2. External Libraries or Applications

   The  following  libraries  or  applications  must  be installed before
   running Kamailio with this module loaded:
     * None.

4. Parameters

   4.1. rtpproxy_sock (string)
   4.2. rtpproxy_disable_tout (integer)
   4.3. rtpproxy_tout (integer)
   4.4. rtpproxy_retr (integer)
   4.5. nortpproxy_str (string)
   4.6. timeout_socket (string)
   4.7. ice_candidate_priority_avp (string)
   4.8. extra_id_pv (string)
   4.9. db_url (string)
   4.10. table_name (string)
   4.11. rtp_inst_pvar (string)

4.1. rtpproxy_sock (string)

   Used to define the list of RTPPRoxy instances to connect to. These can
   be  UNIX  sockets  or  IPv4/IPv6 UDP sockets. Each modparam entry will
   insert  sockets  into a single set. If no set ID is given, the default
   set ID '0' will be used. To define multiple sets add the set number at
   the  beginning  of  each  parameter  followed  by '=='. Sockets can be
   weighted  by  adding  '=#' to a socket where # is an integer. A socket
   with  a weight of 2 will be chosen twice as often as one with a weight
   of 1.

   Default value is "NONE" (disabled). 

   Example 1.1. Set rtpproxy_sock parameter
...
# single rtproxy
modparam("rtpproxy", "rtpproxy_sock", "udp:localhost:12221")

# multiple rtproxies for LB
modparam("rtpproxy", "rtpproxy_sock",
        "udp:localhost:12221 udp:localhost:12222")

# multiple sets of multiple rtproxies
modparam("rtpproxy", "rtpproxy_sock",
        "1 == udp:localhost:12221 udp:localhost:12222")
modparam("rtpproxy", "rtpproxy_sock",
        "2 == udp:localhost:12225")
...

4.2. rtpproxy_disable_tout (integer)

   Once  RTPProxy  was  found  unreachable  and  marked  as disabled, the
   rtpproxy  module  will  not  attempt  to  establish  communication  to
   RTPProxy for rtpproxy_disable_tout seconds.

   Default value is "60". 

   Example 1.2. Set rtpproxy_disable_tout parameter
...
modparam("rtpproxy", "rtpproxy_disable_tout", 20)
...

4.3. rtpproxy_tout (integer)

   Timeout value in waiting for reply from RTPProxy.

   Default value is "1". 

   Example 1.3. Set rtpproxy_tout parameter
...
modparam("rtpproxy", "rtpproxy_tout", 2)
...

4.4. rtpproxy_retr (integer)

   How  many  times  the  module  should  retry to send and receive after
   timeout was generated.

   Default value is "5". 

   Example 1.4. Set rtpproxy_retr parameter
...
modparam("rtpproxy", "rtpproxy_retr", 2)
...

4.5. nortpproxy_str (string)

   This  parameter  sets  the  SDP attribute used by rtpproxy to mark the
   message's  SDP  attachemnt  with information that it have already been
   changed.

   If empty string, no marker will be added or checked.

Note

   The string must be a complete SDP line, including the EOH (\r\n).

   Default value is "a=nortpproxy:yes\r\n". 

   Example 1.5. Set nortpproxy_str parameter
...
modparam("rtpproxy", "nortpproxy_str", "a=sdpmangled:yes\r\n")
...

4.6. timeout_socket (string)

   The parameter sets the RTP timeout socket, which is transmitted to the
   RTP-Proxy.  It  will  be  used  by the RTP proxy to signal back that a
   media stream timed out.

   If it is an empty string, no timeout socket will be transmitted to the
   RTP-Proxy.

   Default value is "" (nothing). 

   Example 1.6. Set timeout_socket parameter
...
modparam("rtpproxy", "timeout_socket", "xmlrpc:http://127.0.0.1:8000/RPC2")
...

4.7. ice_candidate_priority_avp (string)

   If  specified  and if value of the avp value is not 0, rtpproxy_manage
   function   adds  ICE  relay  candidate  attributes  to  sdp  stream(s)
   containing ICE candidate attributes.

   If  value  of  the  avp  is 1, added candidates have high priority. If
   value of the avp is 2 (default), added candidates have low priority.

   There  is  no  default  value meaning that no ICE relay candidates are
   added in any circumstance. 

   Example 1.7. Set ice_candidate_priority_avp parameter
...
modparam("rtpproxy", "ice_candidate_priority_avp", "$avp(ice_priority)")
...

4.8. extra_id_pv (string)

   The  parameter sets the PV defination to use when the "b" parameter is
   used  on  unforce_rtp_proxy(),  rtpproxy_offer(), rtpproxy_answer() or
   rtpproxy_manage() command.

   Default is empty, the "b" parameter may not be used then.

   Example 1.8. Set extra_id_pv parameter
...
modparam("rtpproxy", "extra_id_pv", "$avp(extra_id)")
...

4.9. db_url (string)

   The  database  URL  to  load rtp_proxy sets from. If this parameter is
   set,  the  module  will  attempt  to  load  the rtpproxy sets from the
   specified database and will ignore any 'rtpproxy_sock' modparams.

   Default is empty, a database will not be used.

   Example 1.9. Set db_url parameter
...
modparam("rtpproxy", "db_url", "mysql://user:passwb@localhost/database")
...

4.10. table_name (string)

   The name of the table containing the rtpproxy sets.

   Default value is "rtpproxy".

   Example 1.10. Set table_name parameter
...
modparam("rtpproxy", "table_name", "my_rtpp_sets")
...

4.11. rtp_inst_pvar (string)

   A  pseudo  variable  to  store  the  chosen  RTPProxy address. If this
   parameter  is  set,  the  instance  URL  will  be  stored in the given
   variable.

   By default, this parameter is not set.

   Example 1.11. Set rtp_inst_pvar parameter
...
modparam("rtpproxy", "rtp_inst_pvar", "$avp(RTP_INSTANCE)")
...

   Example 1.12. rtp_inst_pvar usage
modparam("rtpproxy", "rtpproxy_sock",
        "udp:localhost:12221 udp:localhost:12222")
modparam("rtpproxy", "rtp_inst_pvar", "$var(RTP_INSTANCE)")
...
rtpproxy_manage("eiro");
xlog("L_INFO", "Chose rtpp instance $var(RTP_INSTANCE)\n");
# This will display 'udp:localhost:12222'
...

5. Functions

   5.1. set_rtp_proxy_set(setid) 
   5.2. rtpproxy_offer([flags [, ip_address]]) 
   5.3. rtpproxy_answer([flags [, ip_address]]) 
   5.4. rtpproxy_destroy([flags]) 
   5.5. unforce_rtp_proxy() 
   5.6. rtpproxy_manage([flags [, ip_address]]) 
   5.7. rtpproxy_stream2uac(prompt_name, count), 
   5.8. rtpproxy_stream2uas(prompt_name, count) 
   5.9. rtpproxy_stop_stream2uac(), 
   5.10. start_recording() 
   5.11. rtpproxy_stop_stream2uas(prompt_name, count) 

5.1.  set_rtp_proxy_set(setid)

   Sets   the   Id   of  the  rtpproxy  set  to  be  used  for  the  next
   unforce_rtp_proxy(),     rtpproxy_offer(),     rtpproxy_answer()    or
   rtpproxy_manage() command. The parameter can be an integer or a config
   variable holding an integer.

   This   function   can   be  used  from  REQUEST_ROUTE,  ONREPLY_ROUTE,
   BRANCH_ROUTE.

   Example 1.13. set_rtp_proxy_set usage
...
set_rtp_proxy_set("2");
rtpproxy_offer();
...

5.2.  rtpproxy_offer([flags [, ip_address]])

   Rewrites SDP body to ensure that media is passed through an RTP proxy.
   To  be  invoked on INVITE for the cases the SDPs are in INVITE and 200
   OK and on 200 OK when SDPs are in 200 OK and ACK.

   Meaning of the parameters is as follows:
     * flags - flags to turn on some features.
          + 1  -  append first Via branch to Call-ID when sending command
            to rtpproxy. This can be used to create one media session per
            branch  on  the  rtpproxy. When sending a subsequent "delete"
            command  to  the rtpproxy, you can then stop just the session
            for a specific branch when passing the flag '1' or '2' in the
            "unforce_rtpproxy",  or stop all sessions for a call when not
            passing  one  of  those  two  flags there. This is especially
            useful  if  you  have  serially  forked  call scenarios where
            rtpproxy  gets an "update" command for a new branch, and then
            a  "delete"  command  for  the  previous  branch, which would
            otherwise  delete  the  full  call,  breaking  the subsequent
            "lookup"  for  the new branch. This flag is only supported by
            the ngcp-mediaproxy-ng rtpproxy at the moment!
          + 2  - append second Via branch to Call-ID when sending command
            to rtpproxy. See flag '1' for its meaning.
          + 3  -  behave like flag 1 is set for a request and like flag 2
            is set for a reply.
          + a  -  flags  that  UA  from which message is received doesn't
            support symmetric RTP. (automatically sets the 'r' flag)
          + b  -  append branch specific variable to Call-ID when sending
            command  to  rtpproxy.  This creates one rtpproxy session per
            unique  variable.  Works similar to the 1, 2 and 3 parameter,
            but  is  usefull  when  forking  to  multiple destinations on
            different  address  families  or  network segments, requiring
            different  rtpproxy  parameters.  The variable value is taken
            from  the  "extra_id_pv". When used, it must be used in every
            call       to       rtpproxy_manage(),      rtpproxy_offer(),
            rtpproxy_answer()   and   rtpproxy_destroy()  with  the  same
            contents  of  the  PV.  The  b  parameter  may not be used in
            conjunction  with  the  1,  2  or  3 parameter to use the Via
            branch in the Call-ID.
          + l   -   force  "lookup",  that  is,  only  rewrite  SDP  when
            corresponding  session  already  exists  in the RTP proxy. By
            default is on when the session is to be completed.
          + i,  e - these flags specify the direction of the SIP message.
            These  flags  only  make  sense  when  rtpproxy is running in
            bridge  mode.  'i'  means  internal  network (LAN), 'e' means
            external  network  (WAN). 'i' corresponds to rtpproxy's first
            interface,  'e'  corresponds  to rtpproxy's second interface.
            You  always  have to specify two flags to define the incoming
            network and the outgoing network. For example, 'ie' should be
            used  for  SIP  message received from the local interface and
            sent  out  on  the  external  interface, and 'ei' vice versa.
            Other  options  are  'ii'  and 'ee'. So, for example if a SIP
            requests  is  processed  with  'ie'  flags, the corresponding
            response must be processed with 'ie' flags.
            Note:  As  rtpproxy  in bridge mode s per default asymmetric,
            you  have to specify the 'w' flag for clients behind NAT! See
            also above notes!
          + x  - this flag a shortcut for using the "ie" or "ei"-flags of
            RTP-Proxy,  in order to do automatic bridging between IPv4 on
            the  "internal  network"  and IPv6 on the "external network".
            The  distinction  is  done by the given IP in the SDP, e.g. a
            IPv4  Address  will always call "ie" to the RTPProxy (IPv4(i)
            to  IPv6(e))  and an IPv6Address will always call "ei" to the
            RTPProxy (IPv6(e) to IPv4(i)).
            Note:  Please  note,  that  this will only work properly with
            non-dual-stack   user-agents   or   with  dual-stack  clients
            according  to  RFC6157  (which  suggest  ICE  for  Dual-Stack
            implementations).  This short-cut will not work properly with
            RFC4091  (ANAT)  compatible  clients,  which  suggests having
            different   m-lines   with   different  IP-protocols  grouped
            together.
          + f  -  instructs  rtpproxy to ignore marks inserted by another
            rtpproxy  in  transit to indicate that the session is already
            goes  through  another  proxy.  Allows  creating  a  chain of
            proxies.
          + r  -  flags that IP address in SDP should be trusted. Without
            this  flag,  rtpproxy  ignores  address  in  the SDP and uses
            source  address  of the SIP message as media address which is
            passed to the RTP proxy.
          + o  - flags that IP from the origin description (o=) should be
            also changed.
          + c  - flags to change the session-level SDP connection (c=) IP
            if media-description also includes connection information.
          + w  -  flags  that  for the UA from which message is received,
            support symmetric RTP must be forced.
          + zNN  -  requests  the RTPproxy to perform re-packetization of
            RTP  traffic  coming  from  the UA which has sent the current
            message  to  increase  or  decrease payload size per each RTP
            packet  forwarded  if  possible. The NN is the target payload
            size  in  ms, for the most codecs its value should be in 10ms
            increments,  however  for  some  codecs  the  increment could
            differ  (e.g.  30ms  for GSM or 20ms for G.723). The RTPproxy
            would  select  the closest value supported by the codec. This
            feature  could  be  used  for significantly reducing bandwith
            overhead for low bitrate codecs, for example with G.729 going
            from 10ms to 100ms saves two thirds of the network bandwith.
     * ip_address - new SDP IP address.

   This function can be used from ANY_ROUTE.

   Example 1.14. rtpproxy_offer usage
route {
...
    if (is_method("INVITE")) {
        if (has_body("application/sdp")) {
            if (rtpproxy_offer())
                t_on_reply("1");
        } else {
            t_on_reply("2");
        }
    }
    if (is_method("ACK") && has_body("application/sdp"))
        rtpproxy_answer();
...
}

onreply_route[1]
{
...
    if (has_body("application/sdp"))
        rtpproxy_answer();
...
}

onreply_route[2]
{
...
    if (has_body("application/sdp"))
        rtpproxy_offer();
...
}

5.3.  rtpproxy_answer([flags [, ip_address]])

   Rewrites SDP body to ensure that media is passed through an RTP proxy.
   To  be  invoked on 200 OK for the cases the SDPs are in INVITE and 200
   OK and on ACK when SDPs are in 200 OK and ACK.

   See  rtpproxy_answer()  function  description above for the meaning of
   the parameters.

   This   function   can   be  used  from  REQUEST_ROUTE,  ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.15. rtpproxy_answer usage

   See rtpproxy_offer() function example above for example.

5.4.  rtpproxy_destroy([flags])

   Tears down the RTPProxy session for the current call.

   This function can be used from ANY_ROUTE.

   Meaning of the parameters is as follows:
     * flags - flags to turn on some features.
          + 1  -  append first Via branch to Call-ID when sending command
            to rtpproxy. This can be used to create one media session per
            branch  on  the  rtpproxy. When sending a subsequent "delete"
            command  to  the rtpproxy, you can then stop just the session
            for a specific branch when passing the flag '1' or '2' in the
            "unforce_rtpproxy",  or stop all sessions for a call when not
            passing  one  of  those  two  flags there. This is especially
            useful  if  you  have  serially  forked  call scenarios where
            rtpproxy  gets an "update" command for a new branch, and then
            a  "delete"  command  for  the  previous  branch, which would
            otherwise  delete  the  full  call,  breaking  the subsequent
            "lookup"  for  the new branch. This flag is only supported by
            the ngcp-mediaproxy-ng rtpproxy at the moment!
          + 2  - append second Via branch to Call-ID when sending command
            to rtpproxy. See flag '1' for its meaning.
          + b  -  append branch specific variable to Call-ID when sending
            command   to  rtpproxy.  See  rtpproxy_offer()  for  details.
            <listitem>
            </listitem>
            t  -  do  not  include To tag to "delete" command to rtpproxy
            thus  causing  full  call  to be deleted. Useful for deleting
            unused  rtpproxy  call  when  200 OK is received on a branch,
            where rtpproxy is not needed.

   Example 1.16. rtpproxy_destroy usage
...
rtpproxy_destroy();
...

5.5.  unforce_rtp_proxy()

   Same as rtpproxy_destroy().

5.6.  rtpproxy_manage([flags [, ip_address]])

   Manage  the  RTPProxy  session  -  it  combines  the  functionality of
   rtpproxy_offer(),  rtpproxy_answer() and unforce_rtpproxy(), detecting
   internally based on message type and method which one to execute.

   It  can  take  the  same  parameters  as  rtpproxy_offer().  The flags
   parameter   to  rtpproxy_manage()  can  be  a  configuration  variable
   containing the flags as a string.

   Functionality:
     * If INVITE with SDP, then do rtpproxy_offer()
     * If INVITE with SDP, when the tm module is loaded, mark transaction
       with  internal  flag  FL_SDP_BODY to know that the 1xx and 2xx are
       for rtpproxy_answer()
     * If ACK with SDP, then do rtpproxy_answer()
     * If  BYE  or  CANCEL,  or  called within a FAILURE_ROUTE[], then do
       unforce_rtpproxy()
     * If reply to INVITE with code >= 300 do unforce_rtpproxy()
     * If  reply  with  SDP  to  INVITE  having code 1xx and 2xx, then do
       rtpproxy_answer()  if  the  request  had  SDP or tm is not loaded,
       otherwise do rtpproxy_offer()

   This function can be used from ANY_ROUTE.

   Example 1.17. rtpproxy_manage usage
...
rtpproxy_manage();
...

5.7.  rtpproxy_stream2uac(prompt_name, count),

   Instruct  the  RTPproxy to stream prompt/announcement pre-encoded with
   the makeann command from the RTPproxy distribution. The uac/uas suffix
   selects  who  will  hear  the  announcement  relatively to the current
   transaction - UAC or UAS. For example invoking the rtpproxy_stream2uac
   in  the  request  processing  block  on  ACK transaction will play the
   prompt  to  the  UA  that  has generated original INVITE and ACK while
   rtpproxy_stop_stream2uas  on  183  in reply processing block will play
   the prompt to the UA that has generated 183.

   Apart  from  generating announcements, another possible application of
   this  function is implementing music on hold (MOH) functionality. When
   count  is  -1,  the  streaming  will be in loop indefinitely until the
   appropriate rtpproxy_stop_stream2xxx is issued.

   In  order to work correctly, these functions require that a session in
   the RTPproxy already exists. Also those functions don't alter the SDP,
   so  that  they  are  not  a  substitute  for calling rtpproxy_offer or
   rtpproxy_answer.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

   Meaning of the parameters is as follows:
     * prompt_name  -  name  of  the  prompt  to stream. Should be either
       absolute  pathname  or  pathname  relative  to the directory where
       RTPproxy runs.
     * count  - number of times the prompt should be repeated. A value of
       -1  means  that it will be streaming in a loop indefinitely, until
       the appropriate rtpproxy_stop_stream2xxx is issued.

   Example 1.18. rtpproxy_stream2xxx usage
...
    if (is_method("INVITE")) {
        rtpproxy_offer();
        if (detect_hold()) {
            rtpproxy_stream2uas("/var/rtpproxy/prompts/music_on_hold", "-1");
        } else {
            rtpproxy_stop_stream2uas();
        };
    };
...

5.8.  rtpproxy_stream2uas(prompt_name, count)

   See function rtpproxy_stream2uac(prompt_name, count).

5.9.  rtpproxy_stop_stream2uac(),

   Stop  streaming  of  announcement/prompt/MOH started previously by the
   respective  rtpproxy_stream2xxx.  The  uac/uas  suffix  selects  whose
   announcement relatively to tha current transaction should be stopped -
   UAC or UAS.

   These functions can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

5.10.  start_recording()

   This  function  will  send a signal to the RTP-Proxy to record the RTP
   stream  on  the  RTP-Proxy.  This  function is only supported by Sippy
   RTPproxy at the moment!

   This function can be used from REQUEST_ROUTE and ONREPLY_ROUTE.

   Example 1.19. start_recording usage
...
start_recording();
...

5.11.  rtpproxy_stop_stream2uas(prompt_name, count)

   See function rtpproxy_stop_stream2uac(prompt_name, count).

6. Exported Pseudo Variables

   6.1. $rtpstat

6.1. $rtpstat

   Returns the RTP-Statistics from the RTP-Proxy. The RTP-Statistics from
   the  RTP-Proxy  are  provided  as a string and it does contain several
   packet-counters.  The  statistics must be retrieved before the session
   is deleted (before unforce_rtpproxy()).

   Example 1.20. $rtpstat-Usage
...
    append_hf("X-RTP-Statistics: $rtpstat\r\n");
...

7. MI Commands

   7.1. nh_enable_rtpp
   7.2. nh_show_rtpp

7.1. nh_enable_rtpp

   Enables  a rtp proxy if parameter value is greater than 0. Disables it
   if a zero value is given.

   The  first  parameter  is the rtp proxy url (exactly as defined in the
   config file).

   The second parameter value must be a number in decimal.

   NOTE:  if  a  rtpproxy  is  defined  multiple  times  (in  the same or
   different sets), all of its instances will be enabled/disabled.

   Example 1.21.  nh_enable_rtpp usage
...
$ kamctl fifo nh_enable_rtpp udp:192.168.2.133:8081 0
...

7.2. nh_show_rtpp

   Displays  all  the  rtp  proxies and their information: set and status
   (disabled or not, weight and recheck_ticks).

   No parameter.

   Example 1.22.  nh_show_rtpp usage
...
$ kamctl fifo nh_show_rtpp
...

Chapter 2. Frequently Asked Questions

   2.1. What happend with "rtpproxy_disable" parameter?
   2.2. Where can I find more about Kamailio?
   2.3. Where can I post a question about this module?
   2.4. How can I report a bug?

   2.1.

   What happend with "rtpproxy_disable" parameter?

   It was removed as it became obsolete - now "rtpproxy_sock" can take
   empty value to disable the rtpproxy functionality.

   2.2.

   Where can I find more about Kamailio?

   Take a look at http://www.kamailio.org/.

   2.3.

   Where can I post a question about this module?

   First at all check if your question was already answered on one of our
   mailing lists:
     * User Mailing List -
       http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
     * Developer Mailing List -
       http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev

   E-mails regarding any stable Kamailio release should be sent to
   <sr-users@lists.sip-router.org> and e-mails regarding development
   versions should be sent to <sr-dev@lists.sip-router.org>.

   If you want to keep the mail private, send it to
   <sr-users@lists.sip-router.org>.

   2.4.

   How can I report a bug?

   Please follow the guidelines provided at:
   http://sip-router.org/tracker.