Mobile phone calls in sounding muffled or like in a bath

[techies]

Hi
got a azure hosted 3CX PBX. Fanvill x5u. Virgin 100Mb Leased line. SIP t4. Most calls OK unortunatly client has a lot of staff on Vodaphone mobile phones. When they call in the calls are muffled. If they call them back then they are OK. Any ideas please?

 

[Alphabetic]

You've not mentioned provisioning method of your Fanvils?

My guess is an SBC would sort you right out.

 

[leejor]

If it is only Vodafone callers affected, then I'd suspect a Codec issue. You might want to Wireshark, or check the 3CXActivity Log to see if Vodafone calls appear to differ with respect to the Codecs used. You might want to see if you can limit Codec choice. It may also be something between Vodafone and your VoIP provider as well. You might consider enlisting the providers help on this if you don't make any progress.

 

[techies]

Thanks,
Why is it better calling out do you think?

 

[leejor]

Perhaps, because you (3CX), are/ is choosing the Codec?