Automatic Testing of Transmissin and Operational Functions of Intertoll Trunks

T h e a d v e n t of nationwide dialing, especially with full a u t o m a t i c a l t e r n a t e routing, has presented additional problems in t h e m a i n t e n a n c e of intertoll t r u n k s . Transmission r e q u i r e m e n t s are more rigorous, t h e intertoll t r u n k connections are more complex, a n d certain irregularities in t h e performance of t h e distance dialing n e t w o r k are difficult to detect. A u t o m a t i c test e q u i p m e n t h a s been provided to aid a n d increase t h e efficiency of over-all testing. T h i s e q u i p m e n t is capable of a u t o m a t i c a l l y 927 928 TIIE BELL SYSTEM TECHNICAL JOURNAL, JULY 1 9 5 6 testing t h e operational (signaling a n d supervisory) f u n c t i o n s of dial-type intertoll t r u n k s , a n d of m a k i n g t w o - w a y transmission loss m e a s u r e m e n t s a n d a noise check at each end. T h e t e s t results m a y be recorded at t h e originating end by m e a n s of a Teletypewriter. A u t o m a t i c t r u n k testing h a s been used for m a n y years in t h e local p l a n t for checking t h e signaling a n d supervisory f e a t u r e s of interoffice t r u n k s . T h e a u t o m a t i c intertoll t r u n k testing e q u i p m e n t serves a similar f u n c t i o n with respect to these operational f e a t u r e s of t h e intertoll t r u n k s . Because published material is available on a u t o m a t i c operational testing,* these f e a t u r e s will n o t be discussed in detail in this p a p e r ; more emphasis is given to t h e transmission testing f e a t u r e s which are new.