Some while ago AVM released firmware version 54.04.70 which added support for an UMTS Internet access, later this year version 54/74.04.76 added more feature to the UMTS uplink.
I always wanted to test VoIP over UMTS using a Fritz!Box, end of July I finally had the time to setup a testing scenario with a stable UMTS coverage. I was so excited about the result that I completely forgot to write a post about the test.
I used a Huawei E220 USB module, which I connected via a 2m USB cable to the Fritz!Box. The cable was necessary to bring the Huawei into a better position and consequently have a better reception. First speed tests showed ~1.5 Mb/s downstream and ~1Mb/s upstream using VOXmobile‘s mobile network, the throughput is OK for the location of my test, which is rather rural. The SIP setup and registration just worked fine, as you would expect from a Fritz!Box. Calling out and in also just worked fine, I didn’t detect any difference in quality compared with an ADSL access. Of course the latency was higher however if the person you’re calling is not in the same room you don’t even notice the slightly higher latency. I used the iLBC codec, it leaves you some bandwidth for random internet access like IM and eMail.