Telephony - Outbox AI

Overview

Outbox AI supports three carriers: Twilio, Vonage, and Telnyx. Each shines in different markets and price brackets. This guide will help you pick the right one for every client.

Quick Recommendation: - 🇺🇸 US/Canada traffic? Use Twilio (best reliability and features) - 🌍 International traffic? Use Vonage (per-second billing saves money) - 💰 Cost-conscious international? Use Telnyx + Twilio combo (best rates in AU/UK/NZ/Europe)

Choosing a Provider

Compare the three carriers to find the best fit for your use case.

Twilio

Best for: United States (and Canada)

Strengths

✅ Quick, self-serve setup—buy numbers in minutes
✅ High concurrency limits—perfect for large campaigns
✅ Built-in voicemail detection (saves wasted agent talk-time)
✅ Verified Caller ID lets you mask calls with a client’s existing phone number
✅ Direct GoHighLevel SMS integration—same number for calls and texts

Weak Points

❌ Charges by the minute (rounded up), so a 9-second voicemail costs a full minute
❌ Non-US pricing is steep—about 7¢ USD per minute in Australia

Rule of thumb: If the traffic is US-centric, stick with Twilio every time.

Vonage

Best for: Non-US regions where per-second billing matters

Strengths

✅ Bills per second—a 30-second call costs half a minute
✅ Slightly cheaper headline rates than Twilio outside the US

Weak Points

❌ No native voicemail detection (Outbox uses its own transcript-based fallback)
❌ No verified caller IDs
❌ On-boarding is manual: email a rep, fill in forms, wait for approval
❌ No GoHighLevel SMS tie-in, so you’ll juggle separate SMS and voice numbers

When to use: Mid-size international campaigns where per-second pricing outweighs the admin hassle.

Telnyx

Best for: International markets (AU, UK, NZ, Europe) when cost is king and you still want Caller ID masking

Strengths

✅ Significantly cheaper than Twilio in most international markets (40-60% savings)
✅ Supports verified caller IDs—pair it with a Twilio SMS number for a “one-number” experience
✅ Modern dashboard, good documentation
✅ Competitive rates in AU, UK, NZ, and European countries

Weak Points

❌ Charges by the minute (no per-second savings)
❌ Occasional reliability quirks: sudden number blocks, quirky concurrency caps
❌ No built-in voicemail detection
❌ No direct GoHighLevel SMS integration (hence the Twilio-plus-Telnyx combo)

Practical Hybrid Stack

Twilio for SMS + Inbound

Buy a Twilio number → connect to GoHighLevel for SMS + inbound voice

Telnyx for Outbound

Buy a Telnyx number → set Twilio number as a verified caller ID

Save on Costs

Make outbound calls via Telnyx and save 40-60% on international rates

Works great in: AU, UK, NZ, and most European countries

Twilio Setup

Twilio is the gold standard for US/Canada traffic. Follow these steps to set up a number and connect it to Outbox AI.

1. Create (or Open) a Sub-Account

Visit console.twilio.com

Navigate to Sub-Accounts

Click your workspace name → Sub-Accounts → Create new sub-account

Name Your Sub-Account

Name it after your client to keep billing and logs separate

If Twilio shows multiple “regions”, always leave it on US1 so Outbox AI can reach the logs.

2. Build the Regulatory “Bundle” (If Required)

Many countries require proof-of-business before you can purchase phone numbers. Twilio calls this a “regulatory bundle.”

US/Canada toll-free and local numbers typically don’t require bundles. Mobile numbers in most countries (including AU, UK, NZ) do require compliance documentation.

Navigate to Regulatory Compliance

In the left menu choose Phone Numbers → Regulatory Compliance

Create Bundle

Click Create Bundle and fill in: - Country: Select your target country - Number Type: Mobile, Local, or Toll-Free - Business Type: Independent software vendor (or appropriate category)

Upload Documents

Twilio typically asks for: - Business name - Business address - Business registration number (ABN for AU, EIN for US, Companies House for UK, NZBN for NZ) Accepted documents: - Utility bills - Lease agreements - Business registration certificates - Tax documents Each file must show at least two of the required data points; upload multiple files if needed. Registry Links: - ASIC (Australia) - Companies House (UK) - New Zealand Companies Office

Submit and Wait

Submit; approval usually takes 24-48 hours depending on the country

3. Buy a Phone Number

Navigate to Buy a Number

After the bundle is approved (or immediately for US/Canada), go to Phone Numbers → Buy a number

Filter by Country and Capabilities

Filter for your target country and Capabilities = Voice & SMS

Choose Your Number

Select a number that matches your needs: - Mobile (AU: 614, UK: 447, NZ: 642) - Best for SMS + voice - Local (US/Canada area codes) - Geographic presence - Toll-free (US: 800/888, AU: 1800, UK: 0800) - Free for callers

Buy

Click Buy to purchase the number

Pricing Examples (per minute, rounded up):

Region	Outbound	Inbound
US/Canada	~1¢ USD	~0.5¢ USD
UK	~3¢ USD	~1¢ USD
Australia	~7¢ USD	~1¢ USD
New Zealand	~6¢ USD	~1¢ USD

Check Twilio’s pricing page for exact rates in your country.

4. A2P Registration (US SMS Only)

If you’re sending SMS messages to US numbers, you must register for A2P (Application-to-Person) messaging. This is a US regulation to reduce spam.

Required for US SMS: Without A2P registration, your SMS messages to US numbers will be blocked or heavily throttled (limited to ~5 messages per minute).

What is A2P?

A2P (Application-to-Person) registration is required by US carriers for business SMS messaging. It verifies that you’re a legitimate business sending approved content. Two Options:

Standard Registration (Recommended)

Timeline: 4-6 weeks
Cost: ~$15-50 one-time fee
Throughput: Up to 4,500 messages per minuteRequirements:

Business EIN (Employer Identification Number)
Business website
Business address
Description of your SMS use case
Sample message templates

Navigate to A2P Registration

Twilio Console → Messaging → Regulatory Compliance → A2P 10DLC

Submit your business information and EIN

Create Brand

Describe your brand and how you’ll use SMS

Create Campaign

Define your use case (appointment reminders, customer service, marketing, etc.)Submit sample message templates

Wait for Approval

Approval typically takes 4-6 weeks. You’ll receive email updates on progress

Assign Numbers

Once approved, assign your US numbers to the campaign

Start the A2P process immediately after buying your number. The 4-6 week wait is unavoidable, so don’t delay!

Low Volume (Quick Start)

Timeline: Instant
Cost: Free
Throughput: Only 5-10 messages per minuteIf you’re just testing or sending very low volumes, you can skip full A2P registration. However, your messages will be heavily throttled.

Not suitable for production: Low volume limits make this impractical for real campaigns. Only use for testing or tiny-scale operations.

Non-US Numbers

If you’re not sending SMS to US numbers (e.g., AU → AU, UK → UK), you can skip A2P registration entirely. It’s only required for US SMS traffic.

International SMS: Other countries have their own regulations, but most don’t require pre-registration like the US does. Always check local requirements for your target market.

5. Copy Credentials into Outbox AI

Get Your Credentials

Back in the Twilio console dashboard, copy Account SID and Auth Token

Add to Outbox AI

In Outbox AI, open Telephony → Twilio and paste both values

Select Your Number

The number you just bought appears in the list—select it for outbound voice and SMS

6. (Optional) Add a Verified Caller ID for Masking

If your client wants calls to display their existing business line:

Navigate to Verified Caller IDs

Twilio left menu → Verified Caller IDs → Add new

Enter Business Number

Enter the business number; Twilio sends an SMS or voice code for verification

Verify

Once verified, you can choose that caller ID when launching campaigns

Important: Verified IDs work for outbound only; inbound calls still land on the Twilio number.

Vonage Setup

Vonage bills by the second and can be cheaper than Twilio outside the US, but the onboarding is more manual. Follow these steps to secure a number and connect it to Outbox AI.

1. Log In and Fund the Account

Visit Dashboard

Visit dashboard.nexmo.com (same portal, simply re-branded as Vonage)

Add Balance

Add a small balance—Vonage won’t let you request numbers on a £0 wallet

2. Request a Phone Number

Navigate to Buy Numbers

In the left sidebar, click Phone Numbers → Buy Numbers

Search for Number

Choose the target country and search

Request (Not Buy)

Click Request; instead of instant purchase, the portal creates a ticket

Provide Documents

A Vonage rep emails you for supporting documents—usually: - Proof of business name and address (utility bill, lease, ASIC extract, etc.) - Business registration ID (ABN, Companies House number, EIN, etc.)

Wait for Approval

Email the files back; approval typically lands within 24–48 hours The number appears in your dashboard under My Numbers once approved and billed

3. Grab Your API Credentials

Navigate to API Settings

From the top menu, choose Settings → API Settings

Copy Credentials

Copy the API Key and API Secret

4. Connect Vonage to Outbox AI

Open Integrations

In Outbox AI, open Settings → Company → Integrations

Select Vonage

Select Vonage

Paste Credentials

Paste the API Key and Secret; click Save

Assign Numbers

Your purchased numbers populate in the list—assign as needed to voice agents

Telnyx Setup

Telnyx often offers lower per-minute rates than Twilio in many international markets (especially AU, UK, and Europe), but it lacks GoHighLevel SMS integration and native voicemail detection.

Recommended Strategy

Use Twilio for inbound and SMS (so everything lands in GoHighLevel) Use Telnyx for outbound voice, masking the calls with the same Twilio number through “verified caller ID” This gives you the best of both worlds: Twilio’s reliability + Telnyx’s pricing.

Popular in: Australia, UK, New Zealand, and European markets where Telnyx rates are significantly lower than Twilio.

Step 1 – Secure a Twilio SMS / Inbound Line

Buy Twilio Number

Purchase a Twilio number in your target country, plug the SID & Auth Token into Outbox AI, and connect it to GoHighLevel

Assign to your agent

Keep this number for inbound calls and all texting

Add to GoHighLevel (Optional)

Add this number into your GoHighLevel account if you want SMS Capabilities

Step 2 – Buy a Telnyx Outbound Line

Search and Buy

In Telnyx, choose Numbers → Buy Numbers and purchase a voice-capable number in your target country

Complete Compliance

Complete the compliance prompts (business documents, address, registration number, etc.)

Step 3 – Create a SIP Trunk

Navigate to SIP Trunks

Voice → SIP Trunks → Create SIP Connection

Trunk Details

Name it, choose FQDN mode, click Create

Authentication & Routing

Leave FQDN empty and scroll down to Outbound Calls Authentication - Set a unique Username (e.g., outbox_user) - Set a strong Password

Click Next

Configuration

Leave this screen as the defaults and click Next

Inbound

Leave this screen as the defaults and click Next

Outbound Settings

Configure your outbound call settings: - Localization Country – Select the country you’ll be calling (e.g., Australia, US, UK) - Caller ID Override – Paste the Twilio number you purchased in Step 1 This makes outbound calls display your Twilio number instead of the raw Telnyx number.

Configure Voice Profile

Create or select a Voice Profile and whitelist the destinations you plan to dial

Assign Number

Assign the Telnyx number to this SIP trunk

Step 4 – Add Telnyx Number to Outbox AI

Now connect the Telnyx SIP trunk to Outbox AI.

Navigate to Phone Numbers

In Outbox AI, go to Company Settings → Phone Number tab

Add SIP Number

Click Add SIP Number

Configure SIP Details

Fill in the connection details: - Name – Label for this number (e.g., “Client Name - Telnyx Outbound”) - Phone Number – The Telnyx number you purchased (e.g., +61412345678) - SIP Domain – sip.telnyx.com (or 192.76.120.10 if that doesn’t work) - SIP Username – The username you set in Step 3 - SIP Password – The password you set in Step 3

Configure Billing

Set your billing preferences: - Rebilling – Toggle ON if you want to charge clients for usage, OFF if you’re covering costs - Outbound Cost – Set to 0.033 (3.3¢ per minute for AU, adjust for other countries) - Billing Type – Keep Bill per minute ON (Telnyx charges by the minute)

Save

Click Save to add the number to your account

Rebilling: If enabled, Outbox AI will automatically charge your clients based on their call usage at the rate you set. Perfect for agency models!

Result

✅ All outbound calls travel via Telnyx (typically 40-60% cheaper than Twilio in most markets)
✅ The callee’s phone displays the familiar Twilio number
✅ Inbound calls and SMS still hit GoHighLevel through Twilio Estimated Savings:

Australia: ~3.3¢/min vs ~7¢/min (save ~50%)
UK: ~2¢/min vs ~3¢/min (save ~33%)
Europe: ~2-3¢/min vs ~4-5¢/min (save ~40%)

Perfect for international agencies! You get Twilio’s reliability for SMS and inbound, with Telnyx’s pricing for outbound calls. The savings really add up on high-volume campaigns.

Cost-Control Reminders

Per-Minute Billing

Telnyx charges by the minute (unlike Vonage’s per-second billing). A 61-second call costs 2 minutes.

Test Concurrency

Telnyx occasionally rate-limits new numbers. If calls start failing, raise a support ticket to increase limits.

Watch for Blocks

Keep an eye on “number blocked” errors mid-campaign. Swap a fresh Telnyx number if needed.

Document Your Stack

With a multi-provider setup (Twilio + Telnyx), document which number does what so your team doesn’t get confused.

Best Practices

Start with One Provider

Don’t try to set up all three at once. Pick the best fit for your primary market and master it first.

US/Canada clients? Twilio
International clients (per-second billing)? Vonage
Cost-conscious international (AU/UK/NZ/Europe)? Telnyx + Twilio combo

Use Sub-Accounts for Client Separation

Create separate sub-accounts (Twilio) or labeled numbers (Vonage/Telnyx) for each client. This makes billing tracking and troubleshooting 10x easier.

Test Before Going Live

Always send test calls before launching campaigns: 1. Test inbound and outbound 2. Verify caller ID displays correctly 3. Check SMS delivery (if applicable) 4. Confirm call quality and latency

Monitor Your Balance

Set up billing alerts in your provider dashboard. Running out of credits mid-campaign is embarrassing and costly.

Document Your Verified Caller IDs

Keep a spreadsheet of which client uses which caller ID, especially if you’re managing multiple masked setups.

Troubleshooting

Numbers Not Appearing in Outbox AI

Problem: You’ve bought a number but it’s not showing up.Solutions:

Double-check credentials (SID, Auth Token, API Key) are correct
Refresh the Outbox AI page
For Twilio, ensure you’re using the correct sub-account credentials
For Telnyx SIP, verify the SIP domain is correct (sip.telnyx.com or 192.76.120.10)

Calls Failing to Connect

Problem: Outbound calls aren’t connecting. Solutions: - Check balance: Ensure your provider account has sufficient funds - Verify number status: Some numbers need activation or compliance approval - Test with a different number: Rule out number-specific issues - Check concurrency limits: You may have hit your max simultaneous calls - Review error logs: Outbox AI shows detailed error messages in Call Logs

Caller ID Not Displaying Correctly

Problem: The wrong number is showing on outbound calls. Solutions: - Twilio: Verify the caller ID is properly verified in Verified Caller IDs - Telnyx: Check the Caller ID Override is set correctly in the SIP trunk - Both: Ensure you’ve selected the correct caller ID in Outbox AI when setting up the campaign

SMS Not Working

Problem: Text messages aren’t sending or receiving. Solutions: - Twilio only: SMS doesn’t work with Vonage or Telnyx in GoHighLevel - Verify the Twilio number has SMS capability enabled - Check that the number is properly connected to GoHighLevel - Ensure you have A2P 10DLC registration if sending to US numbers

High Latency or Poor Call Quality

Problem: Calls have delays or sound choppy. Solutions: - Check your internet connection: Voice requires stable bandwidth - Test from a different location: Rule out local network issues - Try a different SIP region: For Telnyx, switch to a closer POP - Contact provider support: There may be routing issues on their end

Regulatory Bundle Rejected

Problem: Twilio rejected your compliance documents.Solutions:

Ensure documents show at least 2 of 3 required data points (name, address, registration number)
Use recent documents (under 3 months old)
Make sure text is legible (no blurry photos)
Upload multiple documents if one doesn’t cover all requirements
Check the rejection email for specific issues

A2P Registration Stuck or Rejected

Problem: Your A2P 10DLC registration is taking too long or was rejected.Solutions:If Stuck (over 6 weeks):

Contact Twilio support with your campaign ID
Check for any pending actions in the A2P dashboard
Verify your business EIN is valid and matches official records

If Rejected:

Review the rejection reason carefully
Common issues:
- Sample messages look like spam or scams
- Business website doesn’t match your description
- Use case is unclear or too broad
- EIN doesn’t match business name
Revise your campaign description to be more specific
Provide clearer sample message templates
Resubmit with corrections

Pro Tip: Be very specific in your campaign description. Instead of “marketing messages,” say “appointment reminders and booking confirmations for dental practice patients.”

US SMS Still Throttled After A2P

Problem: SMS messages are still slow even after A2P approval.Solutions:

Verify your phone number is actually assigned to the approved campaign
Check campaign status—it may show “approved” but still be processing
Allow 24-48 hours after approval for full throughput to activate
Review your campaign’s assigned throughput tier (some use cases get lower limits)
Contact Twilio if throttling persists beyond 48 hours

Next Steps

Voice Agents

Set up voice agents to handle your calls

GoHighLevel Integration

Connect your phone numbers to GoHighLevel

Chat Agents

Set up SMS responses with chat agents

Prompting Guide

Write better prompts for your agents

​Overview

​Choosing a Provider

​Strengths

​Weak Points

​Strengths

​Weak Points

​Strengths

​Weak Points

​Practical Hybrid Stack

​Twilio Setup

​1. Create (or Open) a Sub-Account

​2. Build the Regulatory “Bundle” (If Required)

​3. Buy a Phone Number

​4. A2P Registration (US SMS Only)

​What is A2P?

​Non-US Numbers

​5. Copy Credentials into Outbox AI

​6. (Optional) Add a Verified Caller ID for Masking

​Vonage Setup

​1. Log In and Fund the Account

​2. Request a Phone Number

​3. Grab Your API Credentials

​4. Connect Vonage to Outbox AI

​Telnyx Setup

Recommended Strategy

​Step 1 – Secure a Twilio SMS / Inbound Line

​Step 2 – Buy a Telnyx Outbound Line

​Step 3 – Create a SIP Trunk

​Step 4 – Add Telnyx Number to Outbox AI

​Result

​Cost-Control Reminders

​Best Practices

​Troubleshooting

​Next Steps

Voice Agents

GoHighLevel Integration

Chat Agents

Prompting Guide

Overview

Choosing a Provider

Strengths

Weak Points

Strengths

Weak Points

Strengths

Weak Points

Practical Hybrid Stack

Twilio Setup

1. Create (or Open) a Sub-Account

2. Build the Regulatory “Bundle” (If Required)

3. Buy a Phone Number

4. A2P Registration (US SMS Only)

What is A2P?

Non-US Numbers

5. Copy Credentials into Outbox AI

6. (Optional) Add a Verified Caller ID for Masking

Vonage Setup

1. Log In and Fund the Account

2. Request a Phone Number

3. Grab Your API Credentials

4. Connect Vonage to Outbox AI

Telnyx Setup

Step 1 – Secure a Twilio SMS / Inbound Line

Step 2 – Buy a Telnyx Outbound Line

Step 3 – Create a SIP Trunk

Step 4 – Add Telnyx Number to Outbox AI

Result

Cost-Control Reminders

Best Practices

Troubleshooting

Next Steps