Asterisk and authuser with a @ in them

When I used asterisk 1.4.x I was able to register to my SIP trunking provider using the line
in my sip.conf file. YYY is in fact XXX with a specific prefix (33 for france). I had to put 2 as my authentication login is and not YYY.

In asterisk it seems that it is not accepted to put a @ in the auth name. Unfortunatly my SIP provider told me that it was accepted in the SIP RFC that authent login contains something like .

Is there a way to have a @ in an auth login in asterisk 1.6 ?
I already tried to put a \ , a ’ , a "…in front of @, unfortunatly it doesn’t work.

Thanks for your help

I have had the same issue. I have not found a solution yet.