We are using a 3CX SMB FREE shared instance with a Generic VoIP Provider (Registration).
The SIP provider is reachable and responds correctly to the initial REGISTER:
401 Unauthorized
WWW-Authenticate: Digest algorithm=MD5, realm="mgw1.mytweak.at", nonce="08cbbeb9"
However, the 3CX SMB instance does not send a second REGISTER containing an Authorization: header.
Instead, it repeatedly retransmits the original REGISTER with:
CSeq: 1 REGISTER
and without Authorization.
The provider confirmed that the 3CX source IP is whitelisted.
The trunk previously worked and became unregistered on 21 July 2026.
Packet capture is available.
The SIP provider is reachable and responds correctly to the initial REGISTER:
401 Unauthorized
WWW-Authenticate: Digest algorithm=MD5, realm="mgw1.mytweak.at", nonce="08cbbeb9"
However, the 3CX SMB instance does not send a second REGISTER containing an Authorization: header.
Instead, it repeatedly retransmits the original REGISTER with:
CSeq: 1 REGISTER
and without Authorization.
The provider confirmed that the 3CX source IP is whitelisted.
The trunk previously worked and became unregistered on 21 July 2026.
Packet capture is available.
