Phone & Voice Billing

Voice is one of the most powerful features in thinnestAI. This page covers exactly how phone numbers and voice calls are billed so there are no surprises.

Phone Number Charges

To make and receive voice calls, you need at least one phone number. There are two ways to get numbers:

Buy from platform — Purchase Vobiz Indian numbers directly through thinnestAI
Import your own (BYOK) — Bring numbers from Twilio, Vobiz, Exotel, Plivo, or Telnyx

Vobiz Indian Numbers (Buy from Platform)

Number Type	Setup Fee	Monthly Rent	First Month Total
Regular DID	₹100	₹590/mo (incl. GST)	₹690
Gujarat DID	₹100	₹708/mo (incl. GST)	₹808
92/140/160 Series	₹100	₹1,000/mo	₹1,100
1800 Toll-Free	₹100	₹1,500/mo	₹1,600

Setup fee is one-time (first month only)
Renewals are monthly at the rent rate (no setup fee)
Billing is INR-native — no USD conversion
Voice call charges: ₹0.50/min (telephony usage)

How Billing Works

When you purchase a number, the setup fee + first month’s rent is charged immediately from your ₹ wallet balance.
Every 30 days, the monthly rent is automatically deducted.
If your balance is insufficient, a grace period begins (see below).

Purchasing a Number

Go to Phone Numbers in the dashboard.
Click Buy Number → Vobiz Indian Numbers.
Search by region or series.
Select a number and confirm — the first month total is deducted.

Releasing a Number

Delete the number from your dashboard to stop future charges. The number is released back to Vobiz and cannot be recovered.

BYOK Phone Numbers (Bring Your Own)

Import phone numbers from your own provider account at zero monthly cost from thinnestAI.

How BYOK Billing Works

Item	Cost
Monthly number fee	₹0 (you pay your provider directly)
AI agent minutes	₹1.50/min platform fee + provider costs
SIP trunk setup	Free

BYOK vs Platform Numbers

Feature	Platform (Vobiz)	BYOK (Any Provider)
Monthly charge	₹590-1,500/mo from wallet	₹0 (pay provider)
Agent minutes	₹1.50/min + provider	₹1.50/min + provider
Auto-renewal	Yes (monthly)	N/A
Number ownership	Platform manages	You manage
On delete	Number released	Number stays in your account

Supported BYOK Providers

Provider	Credentials Needed	Status
Twilio	Account SID + Auth Token	Live
Vobiz	Auth ID + Auth Token	Live
Exotel	API Key + API Token + Account SID + Subdomain	Beta
Plivo	Auth ID + Auth Token	Beta
Telnyx	API Key	Beta

To set up BYOK: Phone Numbers → [Provider Tab] → Enter credentials → Validate → Import.

Per-Minute Voice Call Rates

Voice calls are billed per minute of active call time, rounded up to the nearest 60-second pulse.

Voice Call Cost Breakdown

Every voice call has two cost components:

Component	Rate	Description
Platform fee	₹1.50/min	thinnestAI infrastructure (LiveKit, SIP, bot orchestration)
Provider costs	Varies	STT + TTS + LLM token costs (see below)

Provider Costs (on top of platform fee)

Provider	Type	Rate
Deepgram Nova-2	STT	~$0.0043/min
Sarvam Saarika	STT	₹0.50/min (INR-native)
Cartesia Sonic-3	TTS	~$0.01/1K chars
Sarvam Bulbul	TTS	₹0.10/1K chars (INR-native)
GPT-OSS 20B (Groq)	LLM	Free (ThinnestAI Stack)
GPT-4o-mini	LLM	$0.15/1M input,$ 0.60/1M output

BYOK: If you bring your own API keys for STT/TTS/LLM, provider costs are ₹0 — you pay the provider directly.

What Counts as Call Time

Event	Billed?
Ringing (before pickup)	No
Connected call	Yes
On hold	Yes
Agent processing time	Yes
Call recording	No additional charge

Telephony Charges (SIP/PSTN)

Telephony charges depend on the phone provider:

Provider	Inbound	Outbound
Vobiz (platform)	₹0.50/min	₹0.50/min
Twilio BYOK	You pay Twilio	You pay Twilio
Other BYOK	You pay provider	You pay provider

Auto-Renewal for Phone Numbers

Phone numbers renew automatically each month. Here’s how the process works:

Renewal Flow

7 days before renewal: A reminder notification is sent (dashboard and email).
On renewal date: The monthly fee is deducted from your balance.
Successful renewal: Number remains active for another month.
Insufficient balance: Grace period begins (see below).

Managing Auto-Renewal

You can view all your numbers and their renewal dates:

curl https://api.thinnest.ai/voice/phone-numbers \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "numbers": [
    {
      "id": "pn_abc123",
      "number": "+14155551234",
      "type": "local",
      "monthly_cost": 1.50,
      "provisioned_at": "2026-01-15T00:00:00Z",
      "next_renewal": "2026-04-15T00:00:00Z",
      "status": "active"
    }
  ]
}

Grace Period for Insufficient Funds

If your balance is too low to cover a phone number renewal, thinnestAI doesn’t immediately release your number. Instead, a grace period applies.

How the Grace Period Works

Day	What Happens
Renewal day	Renewal attempt fails. Number enters grace period. Warning notification sent.
Day 1-3	Number remains active. Daily retry of renewal charge.
Day 4-7	Number remains active but inbound calls show a warning. Daily retry continues.
Day 7	If still unpaid, the number is released and may be reassigned.

Avoiding Grace Period Issues

Enable auto-topup: Automatically add funds when your balance is low.
Set spending alerts: Get notified before your balance drops too low.
Monitor renewal dates: Check Settings > Phone Numbers regularly.

If your number enters the grace period:

Add funds to your account immediately.
The next daily retry will succeed and the number stays active.
No additional penalty fees are charged.

Billing Records and History

Every phone-related charge is recorded and accessible.

Viewing Phone Billing Records

From the Dashboard: Go to Settings > Billing > Records and filter by type “Voice” or “Phone Number”. Via the API:

curl "https://api.thinnest.ai/billing/history/{user_id}?type=voice&limit=20" \
  -H "Authorization: Bearer YOUR_API_KEY"

Record Types

Type	Description
`phone_number_provision`	Initial phone number purchase
`phone_number_renewal`	Monthly renewal charge
`voice_call_outbound`	Outbound call charges
`voice_call_inbound`	Inbound call charges
`voice_ai_processing`	AI token usage during calls

Example Billing Record

{
  "id": "bill_voice_123",
  "type": "voice_call_outbound",
  "phone_number": "+14155551234",
  "destination": "+14155559876",
  "duration_seconds": 185,
  "duration_billed_minutes": 4,
  "telephony_cost": 0.08,
  "ai_processing_cost": 0.12,
  "total_cost": 0.20,
  "timestamp": "2026-03-05T14:30:00Z",
  "call_id": "call_abc123"
}

Monthly Statement

Download a monthly statement with all charges:

curl "https://api.thinnest.ai/billing/statement?month=2026-03" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -o statement-march-2026.pdf

Cost Optimization Tips

Use shorter prompts: Concise agent instructions reduce per-call AI costs.
Set call duration limits: Prevent unexpectedly long calls.
Choose efficient models: Faster models (like GPT-4o-mini) work well for voice and cost less.
Release unused numbers: Don’t pay for numbers you’re not using.
Monitor call patterns: Check which agents or campaigns generate the most call minutes.

Next Steps

Billing Overview — General billing and token pricing.
Campaigns — Run voice outreach campaigns.
Deployment — Self-host for custom voice infrastructure.

Introduction

Getting Started

Voice Agents

Agent Capabilities

Channels

Quality & Oversight

Platform

Phone & Voice Billing

Phone & Voice Billing

Phone Number Charges

Vobiz Indian Numbers (Buy from Platform)

How Billing Works

Purchasing a Number

Releasing a Number

BYOK Phone Numbers (Bring Your Own)

How BYOK Billing Works

BYOK vs Platform Numbers

Supported BYOK Providers

Per-Minute Voice Call Rates

Voice Call Cost Breakdown

Provider Costs (on top of platform fee)

What Counts as Call Time

Telephony Charges (SIP/PSTN)

Auto-Renewal for Phone Numbers

Renewal Flow

Managing Auto-Renewal

Grace Period for Insufficient Funds

How the Grace Period Works

Avoiding Grace Period Issues

Billing Records and History

Viewing Phone Billing Records

Record Types

Example Billing Record

Monthly Statement

Cost Optimization Tips

Next Steps

​Phone & Voice Billing

​Phone Number Charges

​Vobiz Indian Numbers (Buy from Platform)

​How Billing Works

​Purchasing a Number

​Releasing a Number

​BYOK Phone Numbers (Bring Your Own)

​How BYOK Billing Works

​BYOK vs Platform Numbers

​Supported BYOK Providers

​Per-Minute Voice Call Rates

​Voice Call Cost Breakdown

​Provider Costs (on top of platform fee)

​What Counts as Call Time

​Telephony Charges (SIP/PSTN)

​Auto-Renewal for Phone Numbers

​Renewal Flow

​Managing Auto-Renewal

​Grace Period for Insufficient Funds

​How the Grace Period Works

​Avoiding Grace Period Issues

​Billing Records and History

​Viewing Phone Billing Records

​Record Types

​Example Billing Record

​Monthly Statement

​Cost Optimization Tips

​Next Steps

Phone & Voice Billing

Phone Number Charges

Vobiz Indian Numbers (Buy from Platform)

How Billing Works

Purchasing a Number

Releasing a Number

BYOK Phone Numbers (Bring Your Own)

How BYOK Billing Works

BYOK vs Platform Numbers

Supported BYOK Providers

Per-Minute Voice Call Rates

Voice Call Cost Breakdown

Provider Costs (on top of platform fee)

What Counts as Call Time

Telephony Charges (SIP/PSTN)

Auto-Renewal for Phone Numbers

Renewal Flow

Managing Auto-Renewal

Grace Period for Insufficient Funds

How the Grace Period Works

Avoiding Grace Period Issues

Billing Records and History

Viewing Phone Billing Records

Record Types

Example Billing Record

Monthly Statement

Cost Optimization Tips

Next Steps