00457nam a22001337a 4500 (pbk) 621.385 TOP Photocopy Topic digital telephony Islamabad Riphah International University 2001 59 p. : ill. 30 cm. Electrical engineering Telephony digital analog digital conversion Digital transmission Digital switching Control memory Digital network FEAS BK 0 0 0 0 RIU RIU 2012-09-12 Photocopy 0 621.385 TOP PH28 2012-09-12 00:00:00 1 2012-09-12 BK 4659 4659