An Extension Telephone
 

* 1.off premises extension (opx)
2.on premises extension
English Related Words* aiff extension
* american telephone and telegraph, inc.
* analog telephone exchange
* anchor line extension kits
* another telephone line
* answer the telephone
* arj extension
* army extension courses
* asm extension
* automated telephone ordering (ato)
* automatic extension
* automatic long distance telephone system
* bak extension
* barrel extension
* bas extension