• Created by Unknown User (dimitris), last modified on Sep 12, 2007

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 6 Next »

This should be a new chapter of a much shorter depth than the previous version. We may work a glossary-like version that explains common terms (20-30) and compares them in various solutions and points to the appropriate term native to each. Include references to outside material for a more detailed analysis.

General Terms

VoIP protocols

There are many protocols involved in the various functions of VoIP services. However, the two most popular protocols used for the signaling of calls are H.323 and SIP. Interoperability of clients to services relies primarily on signaling and secondarily on the exchange of media. For a general discussion of VoIP, check Wikipedia

VoIP codecs

The term codec refers to the method of coding/decoding of the media data (voice and video) to meet bandwidth requirements of the available network channel. A caller device has to support the same codecs as those available on the other side, i.e. the called device or server. Otherwise the exchange of media may not take place, even though call signaling negotiation has been successful. There are many codecs available for voice, the most popular of which are the G.xxx series as standardized by the ITU. The most commonly available codecs are: G.711 - Pulse code modulation (PCM) demanding a 64 kbps channel and  G.729 - Conjugate-structure algebraic-code-excited linear-prediction (CS-ACELP) demading a 8 kbit/s channel. For a general discussion of Voice Codecs, see Wikipedia

VoIP services

Attempting a simple classification of VoIP services, for the purposes of this cookbook, we see:

  •  basic services: registration of endpoint on servers, call routing, location and call translation
  • value-added: voice-mail, missed call notification
  • enhanced communication services: interoperability of voice calls with other media, like video, instant messaging, as well as trusted domain infrastructure to support level of trust indication to the end user

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

ENUM

Golden-tree and unofficial ENUM trees
Differences between infrastructure ENUM

  • No labels