Problem with SIP provider needing custom TOS and uppercase username

Hello

My local SIP provider (which I can't change, since they have a monopoly on the local numbers) has some weird obligations :
- Type of Service (DSCP) must be set to 12 for both SIP and RTP (af12 / 0x30) for the packets to be routed to its private network
- the username contains mix of uppercase and lowercase letters.

Using my fritzbox 7050, I can only change the DSCP values for all voip accounts at once - which means that if I set DSCP to 30, I can connect to my local SIP provider, but not to my other accounts! If I don't set it to 30, I can only connect to my other SIP accounts.

Well, I can "almost" connect to my local SIP provider, because the username is a mix of uppercase and lowercase letters, which my fritzbox insists on converting to all lowercase

I can not fix that in the voip.cfg file since I don't know how the username is encrypted (should not be !)

I tested a GrandStream HT-286 - it registers fine on my local SIP provider network, with the UsErNaMe and the TOS requirements.

But then I can not use it with my fritzbox since the port 5060 of the fritzbox can not be forwarded to the ATA : the HT-286 can perfectly register and receive incoming calls notification, but calls will not even ring.

Could anyone suggest anything to make either the fritzbox alone or the fritzbox + my HT 286 connect to this SIP provider ?

I think siproxd could work, if there was a port of it for the fritzbox

I am using firmware 14.4.26 or a 7050 annex A

Thanks
Guylhem

Well I configured the HT-286 better, so that it can now register and ring etc : I only had to declare the public IP address I use. It nows work fine. But it is a bit stupid to use a sip ATA next to the fritzbox!

avm was not helpful - they did nothing to check the bug I documented. They couldn't even give me the correct information to fix voip.cfg by myself (the username is encrypted - I can not edit it to correct the case)

I guess I will try freetz instead. At least I will be able to fix it myself.