> ## Documentation Index > Fetch the complete documentation index at: https://docs.topcalls.ai/llms.txt > Use this file to discover all available pages before exploring further. # Credit and Billing > How TopCalls billing works: prepaid credit, the per-minute rate, starter credit, how a call reserves and releases credit, and what happens when you run out. TopCalls runs on prepaid credit. Your team has one credit balance, held in dollars, and calls draw on it as they happen. There's no subscription and no plan tier. You buy credit, calls spend it, and you buy more when you want more. ## The Rate \$0.35 per minute of talk time, billed by the second. That's the whole price of a call. Nothing else is metered on top. ## Starter Credit A new team starts with \$10 of starter credit, so you can place real calls before paying for anything. It only pays for calls: you can't move it to another team and you can't spend it on add-ons. Spending draws on starter credit first. Once that's gone, calls come out of purchased credit. ## How a Call Reserves Credit Placing a call puts a hold on your balance for its full `max_duration`, not for the time it actually uses. The unused part comes back when the call ends. You'll notice this once calls overlap. Every call in flight is holding its maximum, so a new call has less to draw on than your balance suggests. It loosens up as those calls finish. ## Running Out When there isn't enough left to hold, the API refuses the call with HTTP `402` and `code: insufficient_quota`. Nothing is charged, and nothing is queued for later. Add credit in Billing, or wait for a call in flight to release its hold, then try again. [Insufficient quota](/guides/making-calls#insufficient-quota) has the full error body. ## Checking Your Balance `GET /v1/balance` reports prepaid credit in integer microdollars (\$1 = 1,000,000), plus the per-minute rate, concurrency slots, and auto-recharge settings. See the [API reference](/api-reference/introduction) for the endpoint and the scope it needs. ## Concurrency Every account includes 20 concurrent calls. That's a limit on how many run at the same time, not on what they cost: the per-minute rate is the same whether one call is running or twenty. ## Auto-recharge and Alerts Auto-recharge buys credit for you when you're running low, so a long campaign doesn't stop partway through. Alerts just tell you, and leave the buying to you. Both are off until you turn them on. You'll find them in Billing. ## Next Steps Placing calls, and handling the 402 when credit runs out. Read your remaining credit with `GET /v1/balance`.