schrieb:
>
> I want a program that, given my IP address and another
> person's IP address, will let us converse with sound i.e.
> make a VOIP call. I'd prefer that no 3rd system (server)
> be involved. We are both using wireless routers.
Any VoIP Program using the SIP protocol is able to do this.
The problem is NAT, which is probably made by your router.
You will have to open a port, normally 5060, for the
signalling of incoming calls to your PC or phone device.
>
> Is this possible? Is there a program that will allow it?
I prefer SJphone which is freely available for lots of systems.
>
> If a 3rd system must be involved, is there a simple PHP
> script that could coordinate making the connection?
If you know the IP the only 3rd system necessary is a STUN
server which just helps to hold the route open over the NAT.
Then just "dial" the IP-number and it is done.
Even commercially available IP-Phones based on the SIP
protocol are able to do this.
So you even do not need a PC.
Wolfgang