Hi Vapi team, I'm reaching out with a few questions regarding how concurrent calls work on your platform. From what I understand, each phone number can handle up to 10 simultaneous lines. I’d appreciate your help in clarifying the following points: How can I check if a specific phone number still has available lines? Is it better to add more phone numbers or to increase the number of lines per number? I understand each number supports 10 lines, but I’d like to confirm. When exactly is a line considered "in use"? Is it when the call is answered, or as soon as the outbound call is attempted? In other words, does this limit mean I can’t initiate more than 10 outbound calls at once per number? Also, if I needed to support 400 call attempts, expecting about 300 to be answered, what setup would you recommend to handle that volume effectively? Thanks in advance for your support! Best, Mariano

By default, Vapi allows 10 concurrent calls (both inbound and outbound) at the account level, not per phone number. For your 400 call volume scenario, you'll need to: 1. Upgrade to an Enterprise plan which can scale to millions of concurrent calls 2. Contact Vapi support directly to configure your specific requirements

// Example API call to check account limits (conceptual)
curl https://api.vapi.ai/account/limits \
     -H "Authorization: Bearer <your_token>"

Sources: - [Vapi Discord Channel](https://discord.com/channels/1211482211119796234/1336441893395103820) - [Vapi Discord Channel](https://discord.com/channels/1211482211119796234/1331702240242700440)

Each phone number on Vapi supports up to 10 simultaneous calls. You can monitor call status via the dashboard or API. If you need more than 10 simultaneous calls, it’s better to add more phone numbers rather than increasing lines per number. A line is considered “in use” once the call is answered. For 400 call attempts (300 expected answered), I recommend using at least 30 phone numbers to handle the load effectively, and consider Vapi Enterprise plan for unlimited concurrency..

Hey Kings thanks for answer! Okay I Will try that approach

Use the GET /phone-number API to list all numbers, monitor call activity with the GET /call endpoint to track usage, and implement call forwarding logic to distribute calls dynamically across available lines..