What is Concurrency?
Concurrency (also known as Concurrent Calls or Channels) refers to the exact number of parallel active calls that are simultaneously progressing through the Vobiz network on your account at any given microsecond.
How Concurrency Limits Work
Every telecom provider uses concurrent call limits to manage hardware capacity. If your application has a Concurrency Limit of 50, it means you can have 50 active phone calls happening at the same time. These could be:
- 50 outbound dials waiting to be answered.
- 50 people actively talking in an AI Voice agent conversation.
- Or any mix thereof.
If 50 calls are currently active and you attempt to dial a 51st call via the REST API, or a 51st inbound caller attempts to reach your Voice XML application, the call will be rejected immediately with a `429 Too Many Requests` or `SIP 503 Service Unavailable`.
Calculating your requirements
When scaling your campaign or business application, consider your average Call Duration (ACD) to know how many channels you need. If you expect to dial 100 people an hour, and each call lasts an hour, you need an exact concurrency of 100.
Learn how to purchase a higher Concurrency Limit →