Worries about IP-Telephony (VoIP)
Alongside all the advantages of IP telephony there are also some unanswered questions. For
example, IP telephony still has to prove its reliability and fail-safe qualities – a strong point of
classic PBXs. Doubts focus on PC technology and the stability of the software making up
network elements like elements and terminals within VoIP. But VoIP has the option of using
PC independent phones alongside PC based phones. Critical components, like gateways to
the public phone network or IP-PBX servers, can be made more fail-safe using clustering.
Speech quality in IP networks depends mainly on three factors:
1. Speech coding and compression, also called codec. Codecs compress the scanned
digital speech signal using special algorithms and so decrease the amount of data to
be transmitted.
2. Packet delay, also called jitter. There is always delay when compressing the speech
signal. Delay also occurs along the transmission route whenever speech packets are
cached in network elements like gateways, routers or IP terminals. Every time this is
done, latency time is increased.
3. Packet loss of speech transmissions, which mostly results in the late delivery of
speech packets.
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| Worries about IP-Telephony (VoIP) |
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