3Com OfficeConnect ISDN Lan Modem

A remote user has been upgraded from a 3Com ImpactIQ ISDN modem to the 3Com OfficeConnectISDN LAN Modem. The LAN modem can connect to the network, but it can’t access resources. I can’t get drives to map, or the remote computer to access the email server. Any thoughts on what is going on here?