[Serusers] budgetone -> ser -> asterisk

I have a budgetone behind nat it registers with ser fine. I can make a call from it to another non nat budgetone fine. In the following scenario budgeton(no nat) -> ser -> asterisk -> ........, things work fine However in the following scenario budgeton(nat) -> ser -> asterisk ->....., asterisk cannot authenticate the forwarded messages from ser If I remove the authentication requirement from asterisk there is no problem. Is there a problem with forwarded authentication when the phone registered with ser is behind nat? Muhammad Nasim TelAppliant Ltd Tel: 020 7740 3492 Int: +44 20 7740 3492 Main: 0845 004 4040 Fax: 0845 004 4040 www.telappliant.com TelAppliant is the UK's provider of IP telephony solutions for small and medium-sized businesses -------------------------------------------------------------------------------- The information in this message is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying or distribution or any action taken or omitted to be taken in reliance on it is prohibited and may be unlawful.