SIP register fails for extension from mobile hotspot

Gigaset Siemens A540 IP

  • First test
    I have created an extension with number 10003.
    I have registered the A450IP with the SIP credentials of the extension.
    I have connected the A540IP to an Ethernet port of my modem router ADSL.
    The SIP registration is successful and I can successfully establish VOIP calls with extension

  • Second test
    Exactly the same as the first test, except this: I connect the A540IP to the Ethernet port of a hotspot mobile 4G (Huawei Wifi 2 Pro E5885ls-93a) instead of to the modem router. The SIP registration fails.

Here is the full log for the first case (registration OK, modem router ADSL)

The IP address of the A540IP is

And here is the full log for the second case (registration KO, hotspot mobile)

The IP address of the A540IP is

Additional info:

  • If I use the SIP accounts that I have with or, the registration of the Gigaset is successful both with modem router and with hotspot mobile.
  • If I use a SIP account that I have with a Dellmont provider (freevoipdeal), the registration of the Gigaset is successful with modem router but it fails with hotspot mobile (so, the Dellmont provider has the same behavior of my freepbx).

In conclusion, there is some settings in the PBX and in the hotspot mobile (and maybe in the Gigaset) that are not compatible. Since the registration is possible with some VOIP providers when the hotspot mobile is used, I would like that in the same conditions it would be possible also with my freepbx.

Which settings should I change in my Freepbx to solve this issue?

Note: since there are providers working well with the hotspot mobile and Gigaset Siemens, I don’t want to change anything in these devices. It must be possible to solve the problem in the settings of Freepbx and I want to solve the problem there.

The opaque parameter isn’t being returned in the failing cases. Is a router messing with the protocol?

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It is hard to say. I would need to take a trace with wireshark. But I want to focus on Freepbx. Whatever wrong can the hotspot mobile do, this doesn’t prevent and from working well. So what’s the difference between these providers and my Freepbx? What should I change in the Freepbx settings or Asterisk conf files to circumvent this?

The source code of pjproject to not make use of opaque in its digest authentication challenges. This might be difficult, as there is probably a good reason for why it is doing it and it is a MUST level requirement for the client.

I think the only other option is to turn of authentication entirely, which is unlikely to be a good idea given you don’t seem to know the source IP address. It is also not something that I believe you can do from the GUI, for extensions, only for trunks.

You could try using a TLS transport, as routers will not be able to mess with it.

On the other hand, a better way is probably to remove the brain damage from the router. This may help, but is a different model:

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I disabled the SIP ALG
This solved the issue!!!
Thank you very much for your detailed explanation and priceless help.

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