Is there any way to route calls and use asterisk as a proxy just in some situations like if i want to call fron ext 1 to ext 2 both inside the lan no t to proxy them and send the reinvites, ans for ex3 to ext1 internet to lan to proxy the signaling an everithing like a media proxy ??
Yes, you just include canreinvite=yes in the sip.conf stanzas for the phones you want to be able to do reinvites - and canreinvite=no for anything you don’t want to be able to do a reinvite.
For example, your internal phones would have “yes” and your SIP service provider would have “no”.