ICS with BT Connect

Has anyone out there had experience with ICS and the "BT Connect" product
(BT Openworld for Business)?

I have shared a dial-up connection between 2 PCs and all works relatively
well. However, the 2nd PC cannot successfully action the dial-up connection.
It is able to request the 1st PC's modem to dial out and commence training
on the line, but each time the connection fails during authorisation and the
modem hangs up. Needless to say, the 1st PC is able to action the connection
each time.

I am confused as the 2nd PC is using the Dial Up Networking settings from
the 1st PC, therefore what is the difference that prevents this a successful
connection?

The 1st PC is running XP Pro and the 2nd PC is running XP Home.

Tony