How are conversations recorded in virtual PBXs?

Question

SIP

Good afternoon! Prompt somebody rummaging in questions of an ip-telephony.
The situation is the following. We receive telephony via sip from Morton Telecom. The following problem appeared, regardless of the load of the Internet channel and the number of calls with an incoming call, instead of a voice, the ringing of a bell (namely, a bell) is heard. This wildly interferes with work, customers complain that they are thrown off. The voice of our operator can be heard clearly.
I called support and they claim that it all depends on the width of the channel.
But according to the logic of things, the recording of conversations takes place on their server, and there, in the recording, this ringing is heard instead of a voice. it would be logical to assume that the distortion of the sound occurs before the signal has passed through our Internet provider. To this, technical support answered me that my thoughts were not correct and that the conversation was recorded after our operator heard the sound. I consider this complete nonsense. But I decided to consult.
And so the question. According to the sip protocol, does the recording of conversations occur before the respondent hears the voice or after?

Answer 1

I would record a debug at the interface with the provider at the time of the problem. In the trace using wireshark, you can play the desired RTP stream. It becomes clear where the problem is.