Difference beetween users.conf and sip.conf

Hello, everyone.
My problem is that when I configure an extension 9XXXXXXXX in users.conf (with asterisk gui) and I dial it from outside, the dialplan always executes the extension s, not 9XXXXXXXX. However if I configure it in sip.conf. everything goes well 9XXXXXXXX is executed.
Please help me resolve this.
Thanks in advance.

What version of asterisk ?
Also what are you placing in sip.conf ? sip.conf is meant for sip realted info only and not dialplan information.

please see this discussion: forums.digium.com/viewtopic.php?t=12826