voice bandwidth requirements

[biglebowski]

I'm trying to calculate the bandwidth required for a new voice recording system. I've been told that as the phone has two RTP streams (tx & rx) the b/w required for recording will be 2x 87 kbps for G711 or 2x 11 kbps for G729. Does this sound accurate?

 

[SalvoPhl]

A single G.711 call consumes an average of 110Kbps with IP header.
G.729 consumes an average of 30Kbps with IP header.

That includes both sending and receiving of voice packets.

Don't see why you'd need to double that number for each call if that's already the total call consumption per call.

 

[biglebowski]

because there are two types of recording for IP

1. is to span the vlan or ports that the phones are plugged into and sniff the RTP packets. this results in a stereo call (left channel = tx & right channel = rx)

2. is to use the built in bridge (BIB) on the phone to send a duplicate media stream to the voice recorder via a SIP trunk. This is a single stream containing both tx & rx

My understanding is that the phone has two RTP streams (tx & rx) so for G729 is it 15 kbps for each stream?

How did you get those values because the cisco bandwidth calc comes out at 11 kbps & 87 kpbs for 729 & 711

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml#samplecalc