Blocking SIP calls

I am using XLite for Taking SIP calls and also the calls are getting forwarded to mobile,
i want to block user to login to SIP(Xlite) and forward all calls to mobile only…
please suggest how it can be done.
ANshul porwal

Delete their sip.conf entry.

Change the dial string for their extension to one that accesses the mobile number.

This should be so obvious, that I suspect you are using some GUI front end. We are not able to support GUI front ends here. For FreePBX use For AsteriskGUI, contact your supplier.