A call-rate limit controls how fast new call attempts can be launched. Concurrent channels limit how many calls can be up at the same time. Different customers stress them differently: an office PBX needs steady channels, an inbound operation needs headroom for peaks, and an outbound campaign launches bursts of attempts when a list is fresh.
On a shared platform without per-customer limits, one customer's peak can consume capacity that belongs to everyone else. Per-account limits give each customer a guaranteed share, so an office PBX, an inbound queue and an outbound campaign can all run on the same network without affecting each other.
The right place to enforce limits is the session border controller, before traffic reaches the carrier. Per-account call-rate and simultaneous-channel limits mean each customer's burst is contained, and everyone else's traffic is unaffected.
Accounts get dedicated call-rate and simultaneous-channel capacity sized to their traffic, burstable on request. Limits are sized to your forecast and raised as you grow, and the acceptable-use policy is written with real traffic peaks in mind, so a busy day is expected and supported.
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