Well, no replies to my previous post - probably too vague. I should have said using SIP trunks. Anyway, I have made progress. I can authenticate my Win32 system on my Linux system, but not vice-versa. I assume this is because I run as root in Linux, but only as a Local Administrator on my company WinXP laptop (and lucky to get that). Can anyone with a greater knowledge of the source code confirm that Asterisk uses calls to the underlying security system to authenticate proxies? That is, when my Win32 system registers with Linux it checks that the Userid/password I specify in the register => userid:password at linux/colinux statement within sip.conf is defined to the Linux system? Otherwise, where is the userid/password for remote proxies to register on me defined within Asterisk? It seems to work if I use a valid Linux Userid/password. Thanks for any pointers Dave ********************************************************************************* This email is intended solely for the use of the individual to whom it is addressed and may contain confidential and/or privileged material. Any views or opinions presented are solely those of the author and do not necessarily represent those of AGCO. If you are not the intended recipient, be advised that you have received this email in error and that any use, dissemination, forwarding, printing or copying of this email is strictly prohibited. Neither AGCO nor the sender accepts any responsibility for viruses and it is your responsibility to scan and virus check the e-mail and its attachment(s) (if any). ********************************************************************************* AGCO Limited, a limited company, registered in England (registered no.509133) with its registered office at Abbey Park Stoneleigh, Kenilworth CV8 2TQ, England. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20071015/ff2d5ff5/attachment.htm