I have the E61 working with Asterisk (http://www.asterisk.org) over WLAN and GPRS for outgoing calls without a problem. The problem is, any time I receive a SIP call over WLAN or GPRS the call rings my E61 and connects, but then immediately drops the voice channel and I see this on the Asterisk CLI:
Jul 2 21:36:06 WARNING: chan_sip.c:3563 process_sdp: Error in codec string 'eo 0/1 RTP/AVP 103'
This is not a firewall issue, as I have the same problem on my WLAN (with a firewall/NAT) and over GPRS which is a public IP. Does the E61 not properly support G711alaw or iLBC?