Running VOIP over a data Network

[moh123321]

                   Hi Everyone,

We are in the process of implementing VOIP in the building for around 1350 staff by using the current IT network (Cat7a),

My questions are:

- The best and highest codec and protocol to get the best voice quality

- the expected bandwidth consumption for the voip over the data network

- is QOS, will add more overhead for the network?

Any other advise(s) you think it can help or to be taken into consideration while implementing such project?

Thanks

M

[Chris Deren]

G722 provides the best quality, it is a wideband codec using the same bandwidth as G711 which is around 90 kbps per call.  QoS does not add overhead, QoS simply classifies, marks, queues and prioritizes traffic.

HTH, please rate all useful posts!

Chris

[kaja_2kj3]

Hi,

   Inaddition to chris valuable points, to explain further on codec,

Narrowband:

G.711, G.726: Offers narrow-band voice with low processing requirements, and with typical bit-rates of 32-64 kbps.

Other narrow-band codecs with compression, such as G.729AB and G.723.1, offer bit-rates as low as 5.3 kbps, but require higher DSP processing horsepower.

Wideband:

G.722: Offers wideband voice with low DSP processing requirement similar to standard G.726 ADPCM. However, it requires a bit-rate of 48-64 kbps per channel.

G.722.2: Offers wideband voice and compresses the bandwidth down to 12.65 kbps per channel. The trade-off is that it requires more processing cycles than G.722.

Please rate if it helps

'Thanks

[moh123321]

So and based on your comments, and the following link

http://www.eetimes.com/design/signal-processing-dsp/4017506/Tip-Wideband-vs-narrowband-VoIP-codecs/

which option should I go for, wideband or narrow band? I know it is affected by the following two factors :

- Network Bandwidth: if the network I have is supporting up to 1 Gig speed ( Cat7a)

- The PABX configuration: Regarding the DSP horsepower, is it depends on the spec. of the PABX ? i.e its processor type?

Thanks

M