Weird audio after putting call on hold

[ZIain]

Hi,

We have an issue for multiple domains where a call is taken fine, then put on hold, and after it is taken off hold or transferred the callers voice goes very weird and sounds almost like a dalek, but is inaudible. This doesn't however happen with every call. I'm not really sure where to start with this so some pointers would be great.

Thanks

 

[Adrian Fretwell]

I would start by looking at the network. Check for packet loss, available bandwidth etc. The intermittent nature of this may suggest that your phones are competing for network bandwidth with another application/user on your network.

 

[ZIain]

Thanks for your input, Adrian. I don't believe it is a packet loss issue though, as it affects different tenants on different networks, albeit the same FPBX server, however that network has a dedicated 100mb connection, and the number of concurrent calls rarely breaks double figures. I have also spent some time monitoring that network for anomalies. Coupled with that is how the issue appears, it always (as far as I know) happens when placing a call on hold or hold then transferring, it's not choppy like bits of the conversation are missing, just sounds very weird like being passed through some weird audio filter, and very often, although I don't believe always, can be resolved by putting the caller on hold again and taking them off hold again. And while this is happening, the quality of other calls isn't affected.

Thanks.

 

[hfoster]

Maybe the codec is being renegotiated in the process? Perhaps badly? Difficult to say without seeing the log/sngrep. I had a lot of headaches trying to get a lovely OPUS/G722 PBX for internal calls, but PCMU/PCMA for SIP trunk calls.

Might be worth trying only allowing PCMA/PCMU for all calls? Disabling the media_mix_inbound_outbound_codecs too, just in case.