Table of Contents
List of Tables
List of Examples
media_port_min parametermedia_port_max parameterskip_failover_codes parametersiprec_start_recording() function with a single SRSsiprec_start_recording() function with multiple SRS serverssiprec_start_recording() function with custom XML values for participantsThis module provides the means to do calls recording using an external recorder - the entity that records the call is not in the media path between the caller and callee, but it is completely separate, thus it can not affect by any means the quality of the conversation. This is done in a standardized manner, using the SIPREC Protocol, thus it can be used by any recorder that implements this protocol.
Since an external server is used to record calls, there are no constraints regarding the location of the recorder, thus it can be placed arbitrary. This offers huge flexibility to your architecture configuration and various means for scaling.
The work for this module has been sponsored by the OrecX Company. This module is fully integrated with the OrecX Call Recording products.
The full architecture of a SIP Media Recording platform is documented in RFC 7245. According to this architecture, this OpenSIPS module implements a SRC (Session Recording Client) that instructs a SRS (Session Recording Server) when new calls are started, the participants of the calls and their profiles. Based on this data, the SRS can decide whether the call should be recorded or not.
From SIP signalling perspective, the module does not change the call flow between the caller and callee. The call is established just as any other calls that are not recorded. But for each call that has SIPREC engaged, a completely separate SIP session is started by the SRC (OpenSIPS) towards the SRS, using the OpenSIPS Back-2-Back module. The INVITE message sent to the SRS contains a multi-part body consisting of two parts:
Recording SDP - the SDP of the Media Server that will fork the RTP to the recorder.
Participants Metadata - an XML-formated document that contains information about the participants. The structure of the document is detailed in RFC 7865.
The SRS can respond with negative reply, indicating that the session does not need to be recorded, or with a positive reply (200 OK), indicating in the SDP body where the media RTP should be sent/forked. When the call ends, the SRC must send a BYE message to the SRS, indicating that the recording should be completed.
Full examples of call flows can be found in RFC 8068.
Since OpenSIPS is a SIP Proxy, it does not have any Media Capabilities by itself. Thus we need to rely on a different Media Server to capture the RTP traffic and fork it to the SRS. This module currently uses the RTPProxy module in OpenSIPS to instruct the RTPProxy Media Server to fork the RTP media to the SRS.
The siprec module supports failover between multiple SRS servers - when calling the siprec_start_recording() function, one can provision more SRS URIs, separated by comma. In this case, OpenSIPS will try to use them in the same order specified, one by one, until either one of them responds with a positive reply (200 OK), or the response code is one of the codes matched by the skip_failover_codes regular expression. In the latter case the call is not recorded at all.
This module only implements the SRC specifications of the SIPREC RFC. In order to have a full recording solution, you will also need a SRS solution such as Oreka - an open-source project provided by OrecX.
Although this module provides all the necessary tools to do calls recording, it does not fully implement the entire SIPREC SRC specifications. This list contains some of the module's limitations:
There is no Recording Indicator played to the callee - since OpenSIPS continues to act as a proxy, there is no way for us to postpone the media between the caller and callee to play a Recording Indicator message.
Cannot handle Recording Sessions initiated by SRS - we do not support the scenario when an SRS suddently decides to record a call in the middle of the dialog.
OpenSIPS cannot be “queried” for ongoing recording sessions - this is scheduled to be implemented in further releases.
The following modules must be loaded before this module:
TM - Transaction module.
Dialog - Dialog module for keeping track of the call.
RTPProxy - RTPProxy module used for controlling the media forked.
B2B_ENTITIES - Back-2-Back module used for communicating with the SRS.
The minimum value of the port used in the SDP sent to the SRS. This value should correlate to the port-range configured in the RTPProxy Media Server.
Default value is “35000”.
The maximum value of the port used in the SDP sent to the SRS. This value should correlate to the port-range configured in the RTPProxy Media Server.
Default value is “65000”.
A regular expression used to specify the codes that should prevent the module from failing over to a new SRS server.
By default any negative reply generates a failover.
Example 1.3. Set skip_failover_codes parameter
...
# do not failover on 408 reply codes
modparam("siprec", "skip_failover_codes", "408")
# do not failover on 408 or 487 reply codes
modparam("siprec", "skip_failover_codes", "408|487")
# do not failover on any 3xx or 4xx reply code
modparam("siprec", "skip_failover_codes", "[34][0-9][0-9]")
...
Calling this function on an initial INVITE engages call recording to SRSs for that call. Note that it does not necessary mean that the call will be recorded - it just means that OpenSIPS will query instruct the SRS that a new call has sterted, but the SRS might decide that the recording is disabled for those participants.
Note that the call recording is not started right away, but only when the call is actually answered - 200 OK is sent by the callee.
Parameters:
srs - a comma-separated list of SRS URIs. These URIs are used in the order specified. See siprec_srs_failover for more information.
group (optional) - an opaque values used by the SIPREC protocol to group calls in certain profiles.
caller (optional) - an XML block containing information about the caller. If absent, the From header is used to build the value from.
callee (optional) - an XML block containing information about the callee. If absent, the To header is used to build the value from.
rtpproxy_sock (string, optional) - the RTPProxy soscket used for this call. If absent, the rtpproxy module will try to detect the proxy used for the initial call, based on the default set provisioned in the rtpproxy module.
media_ip (optional) - the IP that RTPProxy will be streaming media from. If absent 127.0.0.1 will be used.
The function returns false when an internal error is triggered and the call recording setup fails. Otherwise, if all the internal mechanisms are activated, it returns true.
This function can be used from REQUEST_ROUTE.
Example 1.4. Use siprec_start_recording() function with a single SRS
...
if (!has_totag() && is_method("INVITE")) {
$var(srs) = "sip:127.0.0.1";
xlog("Engage SIPREC call recording to $var(srs) for $ci\n");
siprec_start_recording("$var(srs)");
}
...
Example 1.5. Use siprec_start_recording() function with multiple SRS servers
...
if (!has_totag() && is_method("INVITE")) {
$var(srs) = "sip:127.0.0.1, sip:127.0.0.1;transport=TCP";
xlog("Engage SIPREC call recording to servers $var(srs) for $ci in inbound group\n");
siprec_start_recording("$var(srs)", "inbound");
}
...
Example 1.6. Use siprec_start_recording() function with custom XML values for participants
...
$xml(caller_xml) = "<nameID></nameID>";
$xml(caller_xml/nameID.attr/aor) = "sip:6024151234@10.0.0.11:5090";
$xml(caller_xml/nameID) = "<name>test</name>";
siprec_start_recording("$var(srs)",,"$xml(caller_xml/nameID)");
...
Table 2.1. Top contributors by DevScore(1), authored commits(2) and lines added/removed(3)
| Name | DevScore | Commits | Lines ++ | Lines -- | |
|---|---|---|---|---|---|
| 1. | Razvan Crainea (@razvancrainea) | 81 | 41 | 3449 | 647 |
| 2. | Liviu Chircu (@liviuchircu) | 8 | 6 | 27 | 50 |
| 3. | Vlad Patrascu (@rvlad-patrascu) | 5 | 3 | 124 | 50 |
(1) DevScore = author_commits + author_lines_added / (project_lines_added / project_commits) + author_lines_deleted / (project_lines_deleted / project_commits)
(2) including any documentation-related commits, excluding merge commits. Regarding imported patches/code, we do our best to count the work on behalf of the proper owner, as per the "fix_authors" and "mod_renames" arrays in opensips/doc/build-contrib.sh. If you identify any patches/commits which do not get properly attributed to you, please submit a pull request which extends "fix_authors" and/or "mod_renames".
(3) ignoring whitespace edits, renamed files and auto-generated files
Table 2.2. Most recently active contributors(1) to this module
| Name | Commit Activity | |
|---|---|---|
| 1. | Razvan Crainea (@razvancrainea) | Jun 2017 - Jun 2020 |
| 2. | Liviu Chircu (@liviuchircu) | Apr 2018 - Nov 2019 |
| 3. | Vlad Patrascu (@rvlad-patrascu) | Feb 2018 - Apr 2018 |
(1) including any documentation-related commits, excluding merge commits
Last edited by: Razvan Crainea (@razvancrainea), Liviu Chircu (@liviuchircu), Vlad Patrascu (@rvlad-patrascu).
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