I've pasted the MST below and I think that it confirms my theory that the call is being sent back to the CM instead of being routed to the IVR, which is a Nuance Voice Portal if it matters.
This line concerns me:
Contact: "58262500-2599" <sip:20.20.20.20:6001;transport=tls>
I'm not sure where it’s getting this “Contact”, but that would be the DDI range. The only place that "Contact" is programmed is for the Host Map and it's sip:$(user)@10.10.10.10:5060;transport=5060
Thanks for your help!
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1 22:11:25.481 8B <-- SIP Out
From IPAddr: 20.20.20.20 From Port: 6001 Transport: TLS
To IPAddr: 20.20.20.20 To Port: 5061
INVITE sip:2599@mydomain.com SIP/2.0
From: "Anonymous" <sip:anonymous@anonymous.invalid>;tag=80ce823f02fe41aad53db90cb00
To: sip:2599@mydomain.com
Call-ID: 80ce823f02fe41abd53db90cb00
CSeq: 1 INVITE
Max-Forwards: 71
Route: <sip:20.20.20.20:5061;lr;phase=terminating;transport=tls>
Record-Route: <sip:20.20.20.20:6001;lr;transport=tls>
Via: SIP/2.0/TLS 20.20.20.20:6001;branch=z9hG4bK80ce823f02fe41acd53db90cb00
User-Agent: Avaya CM/R015x.02.1.016.4
Supported: timer, replaces, join, histinfo, 100rel
Allow: INVITE, CANCEL, BYE, ACK, PRACK, SUBSCRIBE, NOTIFY, REFER, OPTIONS, INFO, PUBLISH
Contact: "58262500-2599" <sip:20.20.20.20:6001;transport=tls> <not sure where it’s getting this “Contact”, but that would be the DDI range
Session-Expires: 2400;refresher=uac
Min-SE: 2400
P-Asserted-Identity: sip:mydomain.com:6001
Privacy: id
Content-Type: application/sdp
History-Info: <sip:2599@mydomain.com>;index=1
History-Info: "2599" <sip:2599@mydomain.com>;index=1.1
Alert-Info: <cid:external@mydomain.com>;avaya-cm-alert-type=external
Content-Length: 163
v=0
o=- 1 1 IN IP4 20.20.20.20 <Controller IP
s=-
c=IN IP4 20.20.20.30 <MG
b=AS:64
t=0 0
m=audio 2066 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
2 22:11:25.529 8A ==> SIP In
From IPAddr: 20.20.20.20 From Port: 5061 Transport: TLS
To IPAddr: 20.20.20.20 To Port: 0
SIP/2.0 100 Trying
From: "Anonymous" <sip:anonymous@anonymous.invalid>;tag=80ce823f02fe41aad53db90cb00
To: sip:2599@mydomain.com
Call-ID: 80ce823f02fe41abd53db90cb00
CSeq: 1 INVITE
Via: SIP/2.0/TLS 20.20.20.20:6001;received=20.20.20.20;branch=z9hG4bK80ce823f02fe41acd53db90cb00
Content-Length: 0
Organization: mydomain.com
Server: Avaya SIP Enablement Services
3 22:11:25.570 8A ==> SIP In
From IPAddr: 20.20.20.20 From Port: 5061 Transport: TLS
To IPAddr: 20.20.20.20 To Port: 0
SIP/2.0 480 Temporarily Unavailable
From: "Anonymous" <sip:anonymous@anonymous.invalid>;tag=80ce823f02fe41aad53db90cb00
To: sip:2599@mydomain.com;tag=13C6B264EB6774C62811CC45FF97A187140854388591039
Call-ID: 80ce823f02fe41abd53db90cb00
CSeq: 1 INVITE
Via: SIP/2.0/TLS 20.20.20.20:6001;received=20.20.20.20;branch=z9hG4bK80ce823f02fe41acd53db90cb00
Content-Length: 0
Organization: mydomain.com
Server: Avaya SIP Enablement Services
4 22:11:25.571 8B <-- SIP Out
From IPAddr: 20.20.20.20 From Port: 6001 Transport: TLS
To IPAddr: 20.20.20.20 To Port: 5061
ACK sip:2599@mydomain.com SIP/2.0
From: "Anonymous" <sip:anonymous@anonymous.invalid>;tag=80ce823f02fe41aad53db90cb00
To: sip:2599@mydomain.com;tag=13C6B264EB6774C62811CC45FF97A187140854388591039
Call-ID: 80ce823f02fe41abd53db90cb00
Via: SIP/2.0/TLS 20.20.20.20:6001;received=20.20.20.20;branch=z9hG4bK80ce823f02fe41acd53db90cb00
CSeq: 1 ACK
Max-Forwards: 70
Route: <sip:20.20.20.20:5061;lr;phase=terminating;transport=tls>
User-Agent: Avaya CM/R015x.02.1.016.4
Content-Length: 0