Communication ISDN & Analog Modems

I need to access a remote computer using PCANYWHERE 10. I have my ISDN modem running at 64K. The remote computer uses Analog Modem. But we can not establish a connection and the computer says THE REMOTE COMPUTER DOES NOT ANSWER. But i can hear it ringing.Is it at application layer, physical layer or link layer. WHAT CAUSES THIS KIND OF PROBLEM?