MOH On Call Queue Not Working With Twilio

I have switched from VOIP.ms to Twilio for all of my inbound calls.

Before the switch I previously had “Answer Channel” marked to “No”. On hold music worked flawlessly.

After the switch to Twilio I cannot get on hold music unless I mark “Answer Channel” to “Yes”. Then the PBX sends Twilio notification that the call was answered which disables my other software from sending a missed call text back if the caller hangs up while in the queue.

How do I get Twilio to not mark the call answered and keep the on hold music?! I have to have both on hold music and a notification back to Twilio to mark a hung up call as hung up and not answered.

From Twilio:

“When you make a phone call, the destination telephony network may send back SIP response code 180 to indicate that the destination phone is ringing, and then a SIP code 200 when the call is answered. Early media is indicated by SIP code 183.”

And “Charging: Twilio does not consider the call to be “answered” (and doesn’t start charging you) until it has received the SIP 200 response from the destination network.
Usage: Early media can be used to send informational messages, such as hold music or pre-recorded announcements, before the call is officially answered.”

So how do I get the PBX to send that SIP code 183 back to Twilio while it is ringing instead of blindly sending the 180 response that has Twilio provide the ringback tone and not send my MOH. Or, even worse, sending the 200 response before someone in the queue ever picks up.

This website details this perfectly: SIP 180 vs 183 vs Early media – thanhloi2603

This used to work in earlier versions of the PBX but changed at some point where it no longer works.

I have attached the conversation with Twilio detailing how to do this.
twilio conversation.pdf (137.1 KB)

Anybody have any suggestions for this?!

This is a requirement for Twilio and other providers. The call must be answered before the caller is played with any audio.

According to Twilio’s documentation and support staff it is not. This is an issue with the software that started a few updates ago.

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