Dial Up Networking Error 714
Not enough ISDN channels are available to make the call.

With ISDN, you usually have 2 channels per ISDN line, even if you only order a 64k ISDN line, there are 2 channels.

In this error message it appears that only 1 of your ISDN channels is active, either because of a misconfiguration in the modem on your PC, or because of a telco (telephone company) issue with the second channel.