Registration fails with incomplete SIP command

I have a user connecting to our FreePBX but they are showing up in the log as sending an “Unknown command”

This is the line in the log:

NOTICE[29605] chan_sip.c: Unknown SIP command ‘GISTER’ from

They are able to make calls to other extensions but calls to their extension fail.

The user has a SNOM 300 series phone. Other users with similar phones are able to connect. This phone too has been able to connect in the past, but changed physical location and now fails.

Not sure why the command would be truncated like that. But that seems like the cause of the problem.

Turn off SIP ALG in the router at that new location

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---------------------------show the command “GISTER” is wrong?

Truly strange, but GISTER is presumably REGISTER after the packets are fragmented, look to your network’s robustness.

If lots happens all the time then I would reinstall.

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I will look into disabling SIP ALG on the router in the new location.

I doubt it has to do with the server’s network since it is only the one phone that’s producing the problem. But I guess I will look at the client routers MTU.

I did notice it go from EGISTER to GISTER when the phone was connected directly to the router/modem, instead of a switch.

If it’s only the one phone, then look to that phone’s robustness perhaps.

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Yeah if disabling ALG doesn’t help, I think I might order a replacement phone.

That packet is coming through, so the envelope is correct. That means that the payload is the only thing getting screwed up - sounds like a source hardware problem to me too.