A A2P –  Application to person ACD – Average call duration ASR – Answer seisure ratio B B2B – Business-to-business C CDR- Caller detail records CLI -Calling line identification CNAM – Caller ID with Name CoDec – Coder/Decoder CPC – Calling Party Control D DID – Direct Inward Dialing DND – Do not disturb DSP – Digital Signal Processor E E1 – 30 concurrent calls H HD – High Definition I ISP – Internet Service provider IVR-  Interactive voice response L LOA – Letter of authorization M MOS -Mean Opinion Score N NAT- Network address translation P P2P – Person to person PBX – Private Branch Exchange PDD – Post Dial Delay PESQ – Perceptual Evaluation of Speech Quality PSQM – Perceptual Speech Quality Measure R RTT – Round-trip delay time S SBC – Session Border Controllers Nonce Number Once SDP – Session Description Protocol SIP – Session Initiation Protocol SMPP – Short Message Peer-to-Peer SNMP -Simple Network Management Protocol T T1…