Indeed, thanks! Also, i saw that dtmf= should be dtmfmode= ...
But even with that fixed i still have the same symptoms.

in: tcpdump -i eth1 n800-IP -A, from the gateway with asterisk, i can see:

11:31:08.732719 IP 192.168.1.1.11981 > 192.168.1.178.7079: UDP, length 44

11:31:08.738876 IP 192.168.1.178 > 192.168.1.1: ICMP 192.168.1.178 udp port 7079 unreachable, length 80


I got lucky and got a call to go through and had this in asterisk -rvvvvvv just around where it got disconnected after 12 minutes:

[Nov 29 11:34:43] NOTICE[28729]: chan_sip.c:15460 sip_poke_noanswer: Peer 'n800' is now UNREACHABLE! Last qualify: 6

was still working a bit after the previous warning...

[Nov 29 11:35:50] NOTICE[28729]: chan_sip.c:12336 handle_response_peerpoke: Peer 'n800' is now Reachable. (1428ms / 2000ms)

then it died.... "Connection to one or more account lost" in rtcomm.

== Spawn extension (home, 1234, 1) exited non-zero on 'SIP/n800-081edfb8'

i probably hung up my home ATA/Phone here...

[Nov 29 11:36:46] WARNING[28729]: chan_sip.c:12038 handle_response_invite: Re-invite to non-existing call leg on other UA. SIP dialog '347a5eeb-1910-122b-3595-00194fd4ead7'. Giving up.

And after a while i see this.

Same goes with qualify=no, nat=no ... :|