SIP Trunk Capacity Planner

Estimate the number of concurrent call paths (SIP channels) your business needs without paying for unused lines.

Traffic Profile

Total Employees (Phone Users)

Average Calls per Hour (Per User)

4 calls

Average Call Duration (Minutes)

3 mins

Your Capacity Report is Locked

Adjust your traffic details and click Calculate SIP Channels to generate your instant calculation.

📞 Recommended Capacity

Recommended SIP Channels

Concurrent lines needed

Total Traffic

Erlangs (Hours of traffic)

Estimated Users/Line Ratio

0:1

Reality Check: Calculate to see your needed capacity.

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Understanding SIP Trunk Sizing

Unlike old analog lines where every employee needed a dedicated copper wire, SIP trunking allows businesses to share a pool of "lines" (channels). Because employees aren't on the phone 100% of the time, you usually need far fewer SIP channels than actual employees.

What is an Erlang?

An Erlang is a unit of telecommunications traffic measurement. 1 Erlang represents exactly one hour of continuous voice traffic. By determining your peak traffic in Erlangs, we can apply statistical models to guarantee you have enough lines without overpaying.

The 3-to-1 or 4-to-1 Rule

For a typical office environment, a ratio of 3 or 4 users to 1 SIP channel is standard. However, call centers or heavy-phone-use sales teams might need a 1-to-1 ratio.