Worked example: an outbound trunk group offered 17 erlangs in the busy hour and designed for under 1% blockage needs 27 circuits, which gives a grade of service of 0.64 percent.
Checked 2026-09-25
For 17 erlangs of traffic and a GoS of 0.64 percent, you need 27 circuits to handle this traffic load.
- Vendor
- Cisco
- Product
- Cisco IOS VoIP solutions
- Subsystem
- trunk and port sizing
- Deployment
- on-premises
- Region
- not restricted
- Release range
- document updated 2001-07-02
- Checked
- 2026-09-25
Sources
- Traffic Analysis — Cisco Systems · tier 2 current vendor documentation · Traffic Models > Erlang B > Example (17 erlangs outbound trunk group)
Cite this note
APA
WarmTransfer. (2026, September 25). Erlang B and Erlang C for voice and contact center sizing: source note erlang-traffic-engineering-example-17e-27-circuits. WarmTransfer. https://warmtransfer.net/knowledge/claims/erlang-traffic-engineering-example-17e-27-circuits
BibTeX
@misc{warmtransfer-claim-erlang-traffic-engineering-example-17e-27-circuits,
title = {Erlang B and Erlang C for voice and contact center sizing: source note erlang-traffic-engineering-example-17e-27-circuits},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/erlang-traffic-engineering-example-17e-27-circuits},
note = {Source note erlang-traffic-engineering-example-17e-27-circuits, checked 2026-09-25}
}