I am trying to make external calls from the softphone and it says forbidden, I know the sip info is correct, because I can actually connect sometimes , but never disconnect and reconnect right away.
You say that external calls fail.. how about dialing to voicemail or an internal extension?
That would split the problem "handset to PBX" from "PBX to trunk".
If internals work.. less likely a config problem on the softphone.