Intertoll Trunk Net Loss Maintenance under Operator Distance and Direct Distance Dialing

C u r r e n t l y t h e r e are over 230,000,000 long distance calls m a d e in t h e Bell S y s t e m per m o n t h . T h e y range f r o m relatively simple connections involving a single intercity t r u n k to complex connections involving several intercity t r u n k s in t a n d e m , p e r h a p s t o t a l i n g 4,000 miles in length. In each case t h e r e is a toll connecting t r u n k at each end. Almost half of this traffic involves distances over 30 miles. T h e transmission engineer's problem is how to provide uniformly good a n d dependable transmission so t h a t every one of these calls will be satisfactory to t h e customers involved. T o accomplish this requires a m o n g other t h i n g s t h a t : 1. T h e design loss of every t r u n k m u s t be t h e lowest permissible f r o m t h e s t a n d p o i n t of echo, singing, crosstalk a n d noise. 2. T h e a c t u a l loss of every t r u n k m u s t be k e p t close to t h e design loss at all times. M e e t i n g t h e first r e q u i r e m e n t is a m a t t e r of system design a n d circuit l a y o u t engineering. T h e f a c t o r s involved h a v e been covered in a previous article. 1 M e e t i n g t h e second r e q u i r e m e n t is an i m p o r t a n t f u n c t i o n of t h e m a i n t e n a n c e forces a n d is discussed in this article. T H E PROBLEM OF N E T LOSS MAINTENANCE