No Ring Back Tone when making outbound calls with Grandstream IP PBX UCM63XX

No Ringback Tone when making outbound calls with Grandstream IP PBX UCM63XX

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No Ring Back Tone when making outbound calls with Grandstream IP PBX UCM63XX

Description

No ‘ringback tone’ issue on outbound calls occurs when the PBX or UCM receives 183 Session Progress (with SDP) first and then 180 Ringing later from the SIP Service Provider (ITSP). It would be a 183 Session Progress message to play the ‘Early Media’ on the caller’s phone. Also, missing SDP in 183 Session Progress would lead to the caller being unable to hear the ringback tone over the phone.

Figure 1 shows the TATA provider sends 183 Session Progress message

How-to

1. Make sure SIP ALG is disabled at the router.

2. Navigate to Grandstream UCM’s Web UI > PBX Settings > SIP Settings > ToS > Generate In-band Ringing = Yes

3. PBX Settings > SIP Settings > Misc > Check the options “Ignore 180 Response” and “Enable Use of Final SDP”

4. PBX Settings > SIP Settings > ToS > option “100rel” to ‘No’ or ‘Required’

References

https://support.yeastar.com/hc/en-us/articles/7739557102105-Can-t-hear-Ringback-tone-when-making-outgoing-calls-through-Easybell-sip-trunk

https://support.yeastar.com/hc/en-us/articles/360023844114-How-to-Understand-Inband-Progress-Option

https://docs.google.com/forms/d/e/1FAIpQLSfaq0oYEinkvNt-qZB4wXe9ihwNkwHhLUPE7FypZomjdNV9fg/viewform