Oticon's "Instructions for Use" booklet for its new Epoq hearing aids offers this comment on its telecoils:

5. Telecoil use in church, theatre, or cinema

An increasing number of churches, theatres and public buildings often have loop systems installed.  These systems send out wireless sound to be received by the telecoil in your hearing instrument.  Typically, a sign will let you know whether the place has a telecoil.*  Ask your Hearing Care Professional for details. 

*Oticon surely meant to say "whether the place has a hearing loop."