[noushad shaikh]

VoIP is working on UDP but as we know that UDP is connectionless protocol snd the voice is realtime application and must require a dedicated logical connection so TCP can be use for that WHY UDP??

[Tony]

TCP will retansmit lost packets.
UDP won’t.

Retransmission of lost voice packets (for real time voice) is
pointless as by the time the re-transmitted voice packet arrives the part of the conversation to which it belongs will have been played to the destination user(s).

The TCP stack will also delay packets sent after the lost packet
until the lost packet is resent
and acknowledged (head of line blocking).

It is therefore better to lose real time voice packets than re-transmit them.

Losing a small amount of voice packets usually goes unnoticed (the % lost before quality degrades depends upon the CODEC being used).

It is the VoIP protocol stacks that keep a record of the logical channels.

regards

Tony

[Author]

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