Let’s look at the differences between chan_sip and chan_pjsip closer and try to point all the pros and cons out of both drivers to get a better understanding of what better fits your business or personal needs.
Some history
Asterisk-based PBX and servers use a channel driver to communicate along VoIP protocols. Asterisk, at its core, is agnostic and modular; meaning that it can be adapted to different signaling protocols. It utilizes channel drivers to communicate between the core and the outside world. Concerning SIP, the workhorse for the first eight releases has been chan_sip, but that has been retired beginning with Asterisk 12.x. Chan_pjsip has been the channel driver going forward with Asterisk development. It combines the development of the PJSIP open source project and the continued development of Asterisk to be more efficient, robust, and flexible. You may choose to use chan_pjsip solely, or along with chan_sip as needed.| chan_sip | chan_pjsip | |
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Supportability |
No longer receives core support from Asterisk (in 2017) |
Has Core support from Asterisk |
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SRV Record Lookup |
Only reads the first SRV entry |
As many as assigned |
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Architecture |
Integral |
Modular (easy to modify for new feature support). |
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Functionality |
Limited
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- WebRTC - More NAT Aware - Better STUN/ICE Support
|
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Usability/Migration |
N/A |
Requires some time for adaptation for CLI system users |
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Signaling throughput |
~300 calls per second |
~500 calls per second |
|
Resources |
Uses less CPU | Is more efficient with system resources |
Conclusion
Chan_sip based systems don't properly resolve our PoPs' SRV records, which contain 16 IP addresses in each IP block. It only recognizes the first IP address and doesn't take advantage of our redundancy and load balancing capabilities, leading to intermittent inbound call failures. In certain configurations, chan_pjsip is more efficient. More importantly, Asterisk does not provide support, enhancements, or security updates for chan_sip any longer. Asterisk 13.x or newer build with chan_pjsip is what we recommend.
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