How to keep a Telnyx balance from draining overnight

Telnyx SMS and voice pricing mechanics

Telnyx splits message costs into two distinct line items: a base rate and the carrier fee. For local and 10DLC routes, the base price is $0.004 per message part for outbound SMS and $0.004 for inbound SMS. The carrier passthrough is added at cost without any markup. On outbound local SMS, AT&T charges $0.0035 per part, T-Mobile USA charges $0.0045, Verizon Wireless charges $0.0045, and U.S. Cellular charges $0.005. Inbound SMS incurs an extra carrier fee of $0.0035 on AT&T and $0.0025 on T-Mobile USA, while Verizon Wireless and U.S. Cellular have no inbound carrier fees.

In Telnyx's published cost example for 1,000,000 US message parts, the base SMS charge comes to $4,000 ($0.004 per part) and the blended US carrier passthrough adds $3,800 ($0.0038 per part), yielding a total cost of $7,800. If you compare public rate cards from August 2026, Twilio lists US local SMS at $0.0083 plus carrier fees and Vonage lists $0.0079 plus carrier fees, while Telnyx starts from $0.004 plus carrier fees.

Different message primitives carry separate rate cards. Toll-Free SMS costs $0.0055 per part for both outbound and inbound, with MMS at $0.016 per part plus carrier fees. Short Code SMS runs $0.007 per part inbound and outbound, with automatic volume tier discounts starting after 500K messages per month. For local/10DLC traffic, volume discounts kick in automatically only after you clear 100M message parts in a month, dropping the base rate to $0.0020 for the next 150M parts, $0.0015 for the next 250M, $0.0010 for the next 500M, and $0.0005 for the next 1B parts.

You can query current pricing programmatically directly from the Telnyx API endpoints:

GET /v2/public/pricing
GET /v2/public/pricing?primitive=sms

Other communication products carry distinct fees. Phone numbers start at $1.00 per number per month. Voice AI Agents start from $0.05 per minute, the Verify API costs $0.03 per successful verification (with channel delivery billed separately), and Number Lookup starts from $0.0015 per query. Telnyx offers a Pay as you go plan with a $0 monthly minimum spend, a Growth plan with a $2,000 monthly minimum (which grants a 15% discount on Voice, Messaging, and Numbers along with 24/7 chat and phone support), and an Enterprise plan with a $5,000 monthly minimum.

International destinations can blow up budgets unexpectedly if unmanaged. While domestic US routes stay under a cent per part, certain international carriers charge severe fees; for example, Digicel has an outbound carrier passthrough of $0.20 per message part, and Lleida charges $0.04 per part.

How Telnyx auto-recharge actually charges your card

Telnyx uses a prepaid balance model. When you turn on auto-recharge, you set a threshold balance and a recharge amount. When your available balance drops to that threshold, the system initiates a transaction against your primary saved payment method.

Here is the trap that catches engineering teams off guard: auto-recharge is formulated to bring your account up to Threshold + Recharge, rather than simply adding the recharge amount. If an uncontrolled burst of messages pulls your account balance down to -$150 when your threshold is $50 and your recharge amount is $100, Telnyx will charge your card $300 in one transaction to hit the $150 target. When monthly number renewals drop your balance far below the threshold, the resulting single charge can be significantly larger than what you configured.

Telnyx imposes a hard limit on auto-recharge: it can fire a maximum of 10 times in a 24-hour period. This restriction cannot be removed by support. If an issue causes 10 consecutive auto-recharges within a day and those 10 cycles fail to cover your active usage, your balance will deplete and your services will face immediate disruption until you manually submit a payment.

The platform accepts Credit Card, PayPal, Bitcoin, and ACH Direct Debit. Telnyx stores only one active payment method at a time, rejects PO Boxes for billing addresses, and enforces a minimum payment amount of $10 USD. If you use PayPal and your account has access to ACH, Telnyx has applied a 3% transaction fee on those PayPal transactions since July 3, 2023.

New accounts operate under specific constraints. On day one of account creation, new users have a top-up payment limit of $100 across all payment methods. This limit increases by $50 per day unless you remove it by completing Level 2 Verification. Adding any payment method triggers an account review that can take up to 48 hours (excluding weekends). For non-Level 2 verified accounts, the country on your billing address must match the country of your verification phone number. If a card transaction fails, Telnyx sends an immediate automatic email alert; upon success, it sends a PDF receipt.

Mission Control fraud settings to lock down outbound traffic

You cannot rely on application-level rate limiting alone to protect your balance. If an attacker bypasses your frontend auth or finds an exposed endpoint, they can generate hundreds of concurrent requests before your database alerts trip. You need to enforce hard stops inside the Telnyx Mission Control Portal.

Navigate to your Outbound Profiles to apply traffic restrictions at the telecom routing layer. Outbound Profiles allow you to configure:

• Max daily spend limit: caps total dollar consumption across that profile for the day.
• Max destination rate limit: blocks calls or messages if the cost-per-minute or per-message to that destination exceeds your defined ceiling.
• Country blacklists: outright prevents dialing or routing to specific country codes.
• Active concurrent call limits: caps the number of simultaneous active outbound channels.

For teams running international service plans, you can selectively allow or disallow entire geographic regions or specific countries within those regions. If your user base is entirely domestic, disallow all international regions inside your Outbound Profile. This stops rogue traffic from routing to destinations like Digicel ($0.20 per SMS part) or international premium-rate voice routes.

For inbound routing, Telnyx provides channel limit settings directly on connections and outbound profiles. If your architecture shares a single IP address across multiple distinct clients or staging environments, use a Tech Prefix on the connection to cleanly segment traffic. Splitting workloads across multiple outbound profiles attached to the same connection allows you to apply strict daily spend and rate caps to less-trusted workloads while giving production profiles appropriate headroom.

Credential hygiene and unusual traffic alerts

Compromised API tokens and SIP credentials are the most common source of overnight balance wipes. Telnyx API keys hold full account authority; they do not have granular permission scopes. A leaked token can be used to send SMS, place outbound voice calls, and provision new phone numbers.

Rotate your portal password regularly; Telnyx recommends cycling it every 30, 60, or 90 days, and enabling two-factor authentication (2FA) is mandatory for basic operational safety. API key rotation carries no fee inside the portal. If you run SIP trunks, update your SIP connection credentials via API on a set schedule so that credentials embedded in PBX configs or container definitions are systematically deprecated.

Telnyx operates an automated detection system that monitors outbound voice patterns. If the system flags suspicious activity, it dispatches an immediate email alert to your account address. The system specifically scans for:

• Multiple calls placed concurrently or in rapid succession to the exact same destination prefix.
• Multiple ongoing calls routing to the same high-cost destination.
• Multiple long-lived concurrent calls running simultaneously.

Keep an eye out for these notices. If you see one arrive, log in immediately and inspect your active connections.

If your Telnyx API key leaks publicly, you cannot pause it or strip its capabilities. What should you do first? Delete the compromised key immediately inside the portal to kill access, then issue a replacement. For general remediation steps after a credential leak, see What should I do in the first hour after an API key leaks?.

Organizing spend with Billing Groups and Ledger records

Tracking aggregate balance alone makes it difficult to pinpoint which service is driving up costs. In the Telnyx Mission Control Portal, click the Billing Overview item in the top right-hand drop-down menu. Next to Billing in the top navigation bar, you will find Billing Groups.

Billing Groups allow you to tag and organize numbers, messaging profiles, and outbound voice connections by client, microservice, or environment. While you can use the Scheduled Payments toggle to process a set monthly payment on a specific day of the month to prevent service dropouts, Scheduled Payments work alongside auto-recharge rather than replacing it.

At the start of every month, Telnyx generates invoices for the prior month's usage within the first few days. Inside the invoice section, you can generate detailed Ledger & Billing Records for any past billing period. These records can be exported and broken down by Billing Groups or Managed Accounts, giving you the exact breakdown of base rates versus carrier passthrough fees across every project.

Watching balance drops with Costbrake

Telnyx tells you what individual calls and message parts cost, but it does not let you restrict an API key to read-only access or pause a key if spend spikes. Because Telnyx API keys cannot be restricted or paused, Costbrake does not offer brakes (its opt-in, reversible killswitch) on Telnyx accounts. If a key is compromised, you must delete it inside the Telnyx Mission Control Portal.

Costbrake monitors your Telnyx balance continuously by reading the remaining account balance, calculating your spend from the drop between checks (Telnyx processes and deducts taxes a day later). Currently, only USD Telnyx accounts are supported.

Checks run once per hour on the Free plan ($0 for 2 provider connections, 1 seat, and 30 days of history). On the Pro plan ($12 a month or $120 a year for 10 connections, 3 seats, and 50 budgets) and Team plan ($39 a month or $390 a year for 50 connections and unlimited seats), checks run every 5 minutes, tightening to every 2 minutes if a spending spike is active.

A spike alert fires whenever an hour costs more than 3x your 7-day baseline average and is at least $5 higher than usual. You can also configure budget alerts at 50%, 80%, and 100% of your limit, month-end forecast alerts that project the pace of the last 72 hours, and new-charge alerts when an unexpected service billing line passes $1. Pro workspaces deliver alerts to Slack, Discord, and signed webhooks, while Team workspaces add PagerDuty integration.

To connect Telnyx alongside AWS, Google Cloud, Azure, Cloudflare, Vercel, OpenAI, or Anthropic, tell your AI coding agent to handle your agent setup at https://costbrake.com/agent, or add your credentials manually at https://app.costbrake.com/signin.