Short answer
You need one channel for each call you expect to run at the same time at your busiest point, not one per employee. FirstNet sizes SIP trunk channels from your real call traffic, so you avoid both blocked calls and paying for capacity you never use.
In detail
What goes into the sizing:
- Peak concurrent calls, inbound and outbound, at the busiest time of day.
- The number of direct numbers (DIDs) in active use, and which ones need porting.
- Your calling profile across local, mobile, international and premium-rate destinations.
- The size of the backup trunk, where you have one.
A business with 50 staff may need only a fraction of that in simultaneous calls. Too few channels means callers hear a busy signal and outbound calls are blocked; too many wastes spend, because channel licensing is a monthly operating cost.
Bandwidth follows the channel count. FirstNet plans for about 100 Kbps per concurrent call plus 20% headroom on the internet link, so 10 channels need roughly 1.2 Mbps reserved for voice. FirstNet's voice engineers confirm the channel count during solution design, and the platform scales from five users to five thousand without architectural changes.
Source: FirstNet Business Voice Minutes service page →
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