Phones Erlang Codec
Phone profile 1
Phone profile 2
Phone profile 3
Phone profile 4
Phone profile 5
Phone profile 6
Total
Blocking Ratio
Total Trunks   Estimated BW (kbps) 
   

Voice Trunking Calculator
Calculates the number of trunks and estimated VoIP bandwidth required to support the total erlangs in a site using using Erlang B

The total is comprised of up to 6 calling profiles and the associated codecs.

An erlang is essentually the percentage of an hour a phone is active. A value of .2-.3 are common values. More active phones would have a higher erlang.

Bandwidth is estimated by averaging the individual profiles erlangs against the total erlangs. Keep in mind the peak could always be higher. When calculating the bandwidth the following values are used:
 Bandwidth (kbps)  Codec 
 26.8  G.729A (CS-CELP) 8kbps compression 
 82.8  G.711 (PCM) 64kbps uncompressed 
 17.9  G.723.1 (ACELP) 5.3kbps compression 
 18.9  G.723.1 (MP-MLQ) 6.4kbps compression 
 50.8  G.726 (ADPCM) 32kbps compression 
 28.5  G.728 (LD-CELP) 16kbps compression 

The Blocking ratio is the number of calls that would be blocked. .01 is 1 call in a hundred.