Can't get IAX to work

I just rebuilt my Raspberry Pi asterisk server with Raspbian Jessie, Asterisk 13.6 and bcg729 all built from source. It is very similar to the previous system I was running until last Sunday although for reasons I don’t want to revisit I don’t have all the settings I had then. I am using the same network (home network with router to DSL with static IP) as before when everything worked fine.

I have 3 SIP phones on the home network plus a SIP ATA and they all talk to each other fine through asterisk. I have a voip provider who supports IAX and asterisk registers with it and the provider’s web site acknowledges that I am registered.

mordorCLI> iax2 show registry
Host dnsmgr Username Perceived Refresh State N 000000 60 Registered
1 IAX2 registrations.

When I try to place a call, however, it fails with max retries exceeded. I can see with tcpdump that messages (not many, just a send and a response, repeated several times) are passing back and forth on port 4569. I can’t even make a call to the digium pbx with the simplest possible path through my dial plan.

I’m getting that “stuck” feeling and hope that someone might have a clue about what’s going on. Here’s the dial to my voip provider

-- Executing [start@Dialer:1] NoOp("SIP/000BBE1CEBCC-00000003", "Placing Call") in new stack
-- Executing [start@Dialer:2] GotoIf("SIP/000BBE1CEBCC-00000003", "1?:originate,1") in new stack
-- Executing [start@Dialer:3] Dial("SIP/000BBE1CEBCC-00000003", "IAX2/000000:Password@voipms/16475552368") in new stack
-- Called IAX2/000000:Password@voipms/16475552368

[Oct 27 19:38:08] WARNING[4752]: chan_iax2.c:3571 __attempt_transmit: Max retries exceeded to host on IAX2/voipms-26528 (type = 6, subclass = 1, ts=7, seqno=0)

Could it be something different between v11.something I was running before and v13.6?

If I call my number from the voip provider I see an incoming message but nothing on the asterisk console. Not even with IAX2 debug on.

Just in case you’re wondering, I have the firewall off. My router also maps port 4569 to my asterisk system.

root@mordor:/etc/asterisk# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Thanks for your help,