For Net2Phone (the last version) you can configure the ports you want to use. I received a mail from this people, because I had the same question. But I haven't able to find it. Sorry. Ask them.
Desde: Abubakar Saeed
Enviado el: jueves 17 de abril de 1997 11:18
Asunto: Net2Phone Port Address
Could someone tell me the TCP port for Net2phone, Iphone and freetel
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