We try to connect internal sip phones to a provider on an outside provider. I play arround with the inspect sip.
When inspect sip is set, a can do an outgoing call, but when i call this phone, it rings, i pick it up, but i can't hear the other end. With no inspect sip, it's vice versa.
Just for trying, i give an "access-list like access-list outside_access_in extended permit ip any any", but nothing change.
I found some hints with a STUN Server, but my provider does't have STUN Servers.
Any idea, where i must looking for the right way?