We have a 2811 that has a channelized t1 for voice coming into a controller t1 wic card. We also have a data t1 coming into the same exact type of card. (Both services have a seperate card). We are running IOS version 12.4(12) Advanced IP Services.
Several times a day calls come in that ring normally. When the receptionist answers the phone, there is about 5-10 seconds of dead air, then the other end says "hello? are you there" and after that happens everything is A-OK. I have talked to the provider and they have run two tests on their lines that tested frequencies and devices and there were zero errors.
When I do a "show controllers t1 x/x/x" there are over 300 slip seconds and this number increments.
Any advice on what to do? IOS upgrade maybe? Thanks in advance...