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General Terms

VoIP protocols

H.323 and SIP

VoIP codecs

VoIP services

general, value-added and ECS

SIP Proxy server

H.323 Gatekeeper

Agent - client - endpoint

Gateway

Media proxy

PBX

Call routing

NAT traversal

SIP-related Terms

Domain

Identity

TLS

SIP.edu

ITAD/ISN

Telephony Terms

E.164

Definition.
link for National prefixes

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