pcanywhere over isdn

Hi all
I have two machines one win98 the other win2000 both running pcanywhere 10.0 over isdn,they can easily run pcanywhere over analog lines no problem but will not connect over the isdn,the host just drops the call..i have tried different protocols v120 on both ends but still no luck the isdn modem is a zxcel omninet and an mri mr isdn modem on hte other end.I am wondering if any one has come accross this problem before i live in ireland so its european isdn im dealing with
thanks for your time

regards

Gary Mcnamara