T42G - slow incoming audio

[stevem]

Hi,

I have a customer with 4 T42G phones in their office.
Their ADSL connection was poor due to bad copper lines in the area and that wont be resolved for another 2 years when fibre is installed in the area.
They are trialling an alternative broadband delvery - 4G wireless broadband - and it seems to have improved the speed and reliability of the internet.

The problem is that now the phones are having problems.
The phones ring in, but when the call is answered, there is a delay before audio arrives each time. This is around 4 seconds, but can be longer (in testing it has been utpo 40 seconds).
I have upgarded the phone to the latest firmware, changed the jitter buffer settings, forced to lowest possible Codec, but nothing has improved.

Can anyone help with why this could be occuring.??

I have attached a pcap trace.

many thanks,

Steve