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Beginner

Help with some voip terms. Neewby student

Hello, I'm new to this forum. I'd greatly appreciate if any one could help me with some voip related terms. I´m trying to solve a problem about delay but the info confuse me. It contains the terms payload (i understand this, 24 bytes), total frame size (38 bytes) and voiceframe (30 bytes). I don´t understand the last two because i would think that payload and voice frame are the same. The codec is G.723.1. I have read the cisco document "understanding delay in packet voice networks" and i can´t find any difference. Please help me.

4 REPLIES 4
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Cisco Employee

Hi,

Please check if the following helps

https://books.google.co.in/books?id=DoOsh4NsCKwC&pg=PA40&lpg=PA40&dq=payload+%2B+voice+frame+%2B+total+frame+size&source=bl&ots=lH95P9tLXv&sig=UOLI2y5CuXc_M35vSaJFjebD4eU&hl=en&sa=X&ved=0CCoQ6AEwAmoVChMI4aajmKGryAIViBuOCh0yRQBg#v=onepage&q=payload%20%2B%20voice%20frame%20%2B%20total%20frame%20size&f=false

 

Manish

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I read the guide and i didn´t find anything helpful. But the book is very interesting.

 

Thanks.

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Beginner

Hello,

G723.1 is a high complexity codec with some considerable delay while transmitting. When you say delay, what is the exact amount of delay you are facing? What is the call flow, i.e, are the calls traversing through H323?

The complexity of the algorithm is rated at 25, using a relative scale where G.711 is 1 and G.729a is 15. Algorithmic delay is 37.5 ms per frame, with 7.5 ms look-ahead delay. Music or tones such as DTMF or fax tones cannot be transported reliably with this codec, and thus some other method such as G.711 or out-of-band methods should be used to transport these signals. The complexity of the algorithm is below 16 MIPS. 2.2 kilobytes of RAM is needed for codebooks.

 

What is the business requirement for using G723 on the network? Have you tried the same using G729 and still experience the delay?

 

HTH

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Beginner

 

Ok, i'm going to post the question for context.

 

Calculate the total fixed and variable delay from the next topology

a) Assume the codec  G.723.1, Payload: 24 Bytes, Total Framesize: 38 bytes, Voiceframe: 30 bytes.

The problem i have is what´s the difference between voiceframe and payload?

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