Question:  We have 5 of the TEL-1 Telephone Interface Modules that we are using with a Clear-Com Matrix Plus Intercom System for Dial In IFB. The TEL-1 modules have been randomly dropping calls using cell phones and using land lines. The phone lines to the TEL-1's seem to be ok. Since these units are very old, might there be some typical causes to this problem or might there be some service bulletins available for these units that addresses this problem? Are there any extender cards available for these units? Any information provided would be appreciated.
Answer:  The TEL-1 was our first active telephone hybrid --single telco line --  used with the original Matrix--    The TEL-14 will not work with it..

Unfortunately we have nothing to offer that will pin for pin replace the TEL-1 --  We do not have an extender for the card nor service bulletins dealing with this subject.  It is no longer a serviceable / repairable item. 
Contact Clear-Com sales about the possibility of upgrading to the Eclipse Matrix range