56k PCI Modem to run with NT4 (WS)

I have been unable to get a working 56k PCI modem to dial out on system running Windows NT4 Workstaion with service pack 4 or 6 on 2 different systems.Modem sets up on Com2 but no dial out from that port.How do I get the modem to dial out on Com Port3.Any ideas please.