Domain Pass-thru not playing nice w/ DPMA on FreePBX

[Andrew Pumpelly]

As title says - FreePBX behind dsip in dmz mode (FreePBX has pvt IP, dsip is public facing) I'm experimenting to see if the DPMA (Digium Phone Module) on FreePBX works to provision Digium D series, and Sangoma P series phones - all of the provisioning traffic happens via SIP with these. I've got the FQDN in domains in pass-thru mode to the FreePBX instance, but I'm suspecting the rules dsip creates for this, don't take DPMA into account which is using SIP MESSAGE to contact the PBX to get it's config. See the save from SNGREP below..... going the community route for this one, as I'm hoping we sort this out for EVERYONE ;) 

Here's the redacted for privacy .txt I saved from SNGREP of a Sangoma P325 trying to contact the FreePBX via FQDN passthrough: (Mack - I have a non-redacted version if y'all need that, both in .txt and .pcap - you know how to reach me directly @ work)

2025/08/14 16:18:43.175952 <REDACTED UAC PUBLIC IP>:40055 -> <REDACTED DSIP PUBLIC IP>:5060
MESSAGE sip:proxy@<REDACTED PBX FQDN>:5060;transport=udp SIP/2.0
Via: SIP/2.0/UDP 10.226.0.25:5060;rport;branch=z9hG4bKPjc79nIMfaiYb2lCsSonwC9u9fQM6SAuTZ
Max-Forwards: 70
From: <sip:10.226.0.25>;tag=j2fa4PN-nbvkQiqaG-bk9MROkSMJxEAE
To: <sip:proxy@<REDACTED PBX FQDN>>
Call-ID: cR.WGVjNnX.1-r7hPGGuPYPe4zRaowev
CSeq: 53307 MESSAGE
Accept: text/plain, application/im-iscomposing+xml
User-Agent: Sangoma P325 4_24_3
X-Digium-User-Agent: Sangoma P325 4_24_3
X-Digium-AppServer-RequestType: Handshake
X-Digium-Software-Version: 4_24_3
X-Digium-AppServer-MACAddress: <REDACTED DEVICE MAC ADDRESS 000FD3xxxxxx>
X-Digium-AppServer-ID: general2
X-Digium-AppServer-Message-Sequence: 0
Content-Type: text/plain
Content-Length:   500

-----BEGIN CERTIFICATE-----
MIICtDCCAh0CAVUwDQYJKoZIhvcNAQEFBQAwYDELMAkGA1UEBhMCVVMxCzAJBgNV
BAgMAkNBMRIwEAYDVQQHDAlTYW4gRGllZ28xFTATBgNVBAoMDERpZ2l1bSwgSW5j
LjEZMBcGA1UEAwwQRGlnaXVtIEFwcHNlcnZlcjAgFw0yNDEwMjkxOTE1NDZaGA8y
MDU0MTAyMjE5MTU0NlowSzELMAkGA1UEBhMCVVMxCzAJBgNVBAgMAkNBMRQwEgYD
VQQKDAtEaWdpdW0sIEluYzEZMBcGA1UEAwwQRGlnaXVtIEFwcHNlcnZlcjBcMA0G
CSqGSIb3DQEBAQUAA0sAMEgCQQDVQQOqAyjEumvytoci511T7OcjicCRsMK19UDV
z7xG/woAxwBEGxK3j8meudbTBFHMizvXbBNU8DR5zMgdn/3LAgMBAAGjgdkwgdYw
CQYDVR0TBAIwADAuB

2025/08/14 16:18:43.178968 <REDACTED DSIP PUBLIC IP>:5060 -> <REDACTED UAC PUBLIC IP>:40055
SIP/2.0 407 Proxy Authentication Required. Add the PBX or Carrier IP using GUI
Via: SIP/2.0/UDP 10.226.0.25:5060;rport=40055;branch=z9hG4bKPjc79nIMfaiYb2lCsSonwC9u9fQM6SAuTZ;received=<REDACTED UAC PUBLIC IP>
From: <sip:10.226.0.25>;tag=j2fa4PN-nbvkQiqaG-bk9MROkSMJxEAE
To: <sip:proxy@<REDACTED PBX FQDN>>;tag=9dd61ff61e802d8e2bef5f14621ef3c2.841bd45b
Call-ID: cR.WGVjNnX.1-r7hPGGuPYPe4zRaowev
CSeq: 53307 MESSAGE
Server: dSIPRouter/0.78
Content-Length: 0