Plain Old Telephone Service
Plain Old Telephone System
Parents Over The Shoulder
Pat On The Shoulder
Plain Old Telephone Services
postural orthostatic tachycardia syndr…
Pretty Old Tired Stuff
Panel Operator Training Simulator
Pan-only Triangulation System
Plain Old Telephone Set
Plain Old Time Sharing
Plain Old Time-Sharing
Plain Ordinary Telephone Service
Plain Ordinary Telephone System
Point Of Termination Station
Portable Optical Tracking Station
postural tachycardia syndrome
Pretty Old Time Stuff
Publicly owned treatment system
Purchase Of Telecommunications Service…