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porlaiuc- ill the system as a whole. These matters are iDMii'd in 

 routine instriulioiis which are develojied by experience and wbirli 

 take into account local conditions and service recjuirements. 



In conclusion, it may be stated that telephone systems in their 

 present development have at their disposal means for carrying on an 

 adeciuate transmission maintenance program in an economical manner. 

 Furthermore, studies and trials of new methods are continualK- 

 being carried on with a \iew to obtaining further impro\ements 

 and increased economies in transmission testing and maintenance 

 work. 



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