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Each trunk allows either one inbound or outbound call at any point in time, just like a traditional phone line or PRI channel. Additional simultaneous inbound or outbound calls are not delivered if all your channels are being used. You can purchase additional trunks to increase capacity (concurrency).
Our optional Concurrency Bursting Softcap Bursting feature allows you to go beyond your softcap and pay a per-minute fee for additional calls. If you want to ensure that all your calls are always delivered in the event of a burst of traffic exceeding your concurrency, you can enable Concurrency Bursting. The extra calls will be charged at a different per-minute rates depending on whether they are Inbound, Outbound, or Canada Outbound. Enabling Concurrency Bursting in your SIPStation account will automatically enable the Top Up feature, which charges your card a set amount in order to pre-pay for metered services. See our "How Metered Services Work" wiki for more information.
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