[Serusers] Problem with MultiTech MVP130 PBX Gateway

I have SER 0.8.14 running in 2 instances on a P4 Fedora Core 1 with 512MB RAM with SEMS for voicemail. Xten Pro softphones work perfectly. instance one: SER -f /usr/local/etc/ser/ser.cfg -P /var/run/ser.pid instance two: SER -f /usr/local/etc/ser/voicemail.cfg -P /var/run/servm.pid SEMS uses the defaults. All config files are attached. My MVP130 operates in 3 distinct ways, based on the status of the callee. 1) The callee is offline: voicemail picks up immediately. VOIP-200410247 is the tcpdump. You see the RTP traffic come back from SER immediately, and you can hear the message on the phone, but at the word "possible" in the "call isn't available" message, the MVP130 hangs up, as though it's recieved a "BYE" message. I can't see why. 2) The Callee is online, but ignores the call (either VOIP-20041027 or VOIP-20041027-2) The phone rings forever, even past the "network timeout" setting configured on the MVP130. Traces show the RTP traffic headed back to the client, but you never hear it on the phone. 3) Callee is online, but SIP traffic fails to tranmit the NAT router, so the invite fails. This works flawlessly with the transfer to voicemail (The NAT transversal is a failure of the firewall, not NATHELPER, afaik). Thanks in advance - all the information here is so good! Rob