Hello,
The real required bandwidth depends on many factors like CODEC, no. of samples per IP packet, Header compression, tunnel header overhead and so on.
As this requires much more insight into your VoIP solution and network design to give a definate answer, I would suggest you to go through "Voice Over IP - Per Call Bandwidth Consumption" at
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml
This will guide you to be able to do the calculations on your own for your environment. Just keep in mind, that you need to add additional tunnel headers like GRE or IPSec to properly calculate the required bandwidth per call.
Hope this helps! Please rate all posts.
Regards, Martin
