The first thing you should do when intermittent FAX completion occurs is to initialize th FAX machine as follows:
1. unplug the telephone line cord to the wall jack, then unplug the power AC cord for 30 seconds.
2. After the 30 seconds, then reconnect the line cord to the wall jack, then reconnect the AC power cord.
If this does not work, then you should consider connecting a telephone to the FAX phone extension jack and make sure you have dial tone before sending any FAX. Also make sure your FAX has all its correct settings for receiving and tramsmitting faxcimile. If you continue to have these intermittent/incomplete FAX transmssion issues, contact Comcast at 18003913000 use option 2 and have the technical agent reset your business telephone modem.