How Credits Work

Credit Deduction Flow

Every voice call follows this billing flow:

1. Pre-Call Balance Check

When you start a call (web, phone, widget, or WhatsApp), letustalk.ai checks your balance:

Balance >= $0.10 → Call proceeds
Balance < $0.10  → HTTP 402: "Insufficient credits"

2. During the Call

While the call is active, the voice bot collects usage metrics in real-time:

• Prompt tokens — LLM input tokens consumed
• Completion tokens — LLM output tokens generated
• TTS characters — Characters converted to speech
• Duration — Total call length in seconds

No credits are deducted during the call.

3. After the Call

When the call ends, letustalk.ai:

1. Calculates the total cost based on the agent's provider configuration and actual usage
2. Deducts credits atomically — if balance is insufficient, the call is marked as "billing failed"
3. Records a transaction for your billing history

Example

A 5-minute phone call using GPT-4o + Deepgram:

LLM:  2,400 tokens → $0.018
STT:  5 minutes    → $0.028
TTS:  1,800 chars  → $0.036
SIP:  5 minutes    → $0.050
─────────────────────────
Total deducted:      $0.132

Billing Status

Each call has a billing status visible in your Call Logs:

Promotional Credits

letustalk.ai supports two types of credit balances, both visible as separate cards on the Billing page:

Deduction Order

When a call is billed, credits are deducted in this order:

1. Promotional Credits (promo balance) → deducted first
2. General Credits (paid balance)      → used when promo is exhausted

This means coupon credits are always consumed before any paid credits, maximising the value of your promotions.

Currency

All credits are in USD ($). Provider costs are billed in USD with our standard margin applied.