Trunk Failed - Missing Digest algorithm in 401 response


New Member
Jun 6, 2023
Hello all,

I have been following this forum for a long time and have resolved many questions with your help. However, I am currently facing an issue that I cannot resolve, and I will explain it to you:

One of my SIP providers does not send the algorithm field in the 401 (Unauthorized) response when we attempt to register. What they send is:

WWW-Authenticate: Digest realm="", nonce="dfrAdsdCdRA3adfswDKGFOSk"

In response to the previous 401 (Unauthorized), we reply with another Register with the Authorization field constructed as follows:

Authorization: Digest username="user", realm="", nonce="ssaffgsWifdrtRssDdaGek", algorithm=MD5, uri=";transport=udp", response="3gDsdgfsgCdOf0gh34sdCAPd04"

We receive another 401 (Unauthorized) and cannot register the trunk.

In the FreeSWITCH log, we get the following message:

"Failed Registration with status Operation has no matching challenge [904]. failure #2"

We have a trunk with a different provider that responds to the first Register with a 401 (Unauthorized), but in this case, it does return a WWW-Authenticate indicating algorithm=MD5.

"WWW-Authenticate: Digest algorithm=MD5, realm="blablabla", nonce="6456fgchdasfdGe""

In the case of this new trunk, we register correctly.

All tests have been made with FusionPBX 5.2.

We have tried several trunks from the first provider with the same results.

We have another FusionPBX (4.5.29) where the trunks from this provider register correctly.

Why does this behavior occur?
How can we resolve the lack of the "algorithm" value in the "WWW-Authenticate" field in the 401 responses so that the trunk registers?

Thanks in advance,