Sip to PRI call failing Retransmission timeout reached on transmission

[kits]

I am trying to setup a SIP to PRI from Asterisk on 908E. Outbound calls are working fine however when attempting to place an inbound call it rings 2 times then hangs up.

When checking Adtran debug VOICE VERBOSE or isdn l2-formatted shows no activity while SIP STACK MESSAGE shows the asterisk box sending invites but there is never a response?

Why would there be no response from the adtran to the sip messages?

Asterisk Debug

  == Using SIP RTP CoS mark 5

    -- Called SIP/5551212@333333

    -- Local/5551219@TI1000-000012c0;1 is ringing

[Aug 27 16:27:38] WARNING[25105]: chan_sip.c:3824 retrans_pkt: Retransmission timeout reached on transmission 23677cfd20fda9c568c63223411643e5@1.1.1.1:5060 for seqno 102 (Critical Request) -- See https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions

Packet timed out after 6400ms with no response

[Aug 27 16:27:38] WARNING[25105]: chan_sip.c:3853 retrans_pkt: Hanging up call 23677cfd20fda9c568c63223411643e5@1.1.1.1:5060 - no reply to our critical packet (see https://wiki.asterisk.org/wiki/display/AST/SIP+Retransmissions).

  == Everyone is busy/congested at this time (1:0/0/1)

[kits]

I was able to resolve this issue by checking: debug sip cldu. The issue was related to the 908 receiving the INVITE at the public IP instead of the natted IP.

ERROR! Request-URI host is not local, unable to proxy incoming message to

Hope this is helpful to anyone experiencing similar.