We are experiencing a problem on the Nokia E-61 (firmware version 2.0618.06.05 / 14-07-06 / RM-89) with incoming SIP calls where the incoming INVITE does not contain an SDP.
Here is the SIP call flow involved:
1. E-61 receives an INVITE from the Remote SIP Endpoint, no SDP provided
2. E-61 sends 100/Trying to the Remote SIP Endpoint
3. E-61 sends 180/Trying to the Remote SIP Endpoint
4. E-61 sends 200/OK to the Remote SIP Endpoint that contains the SDP of the handset
5. E-61 receives ACK from the Remote SIP Endpoint that contains the SDP of the remote.
The SIP signaling looks good. However, after the Nokia E-61 receives the ACK (step 5), the RTP channel between the two endpoints does not appear to be setup properly (in both directions); we can hear noise in one direction (Remote SIP Endpoint->Nokia E-61) and silence in the other direction. You will find attached to this message the Ethereal/Wireshark trace of the SIP exchange (incoming.pcap) between the two endpoints.
It might be worth noting that we also installed the latest firmware (version 3.0633.09.04 / 20-11-06 / RM-89) on another Nokia E-61 device and the device reboots upon accepting the incoming SIP call (using the same conditions as stated above).
Please note that the Nokia E-61 handles incoming SIP calls with SDP (in the incoming INVITE) and outgoing SIP calls just fine; the RTP channel is setup properly in both directions.