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How to set up SMS support with AskVault

Written by Joseph Russo, Principal Architect, Networks and Tech, AskVault · Reviewed by Allison Chan
Last updated: · 5 min read

When SMS is the right channel

SMS makes sense for three patterns. Order-status alerts where you want a one-shot Q&A flow ("text STATUS to 12345 for your order"). Appointment reminders and confirmations for services. Outbound notifications where the customer can reply with a question. For real-time conversational support of complex topics, WhatsApp is usually better. SMS is a polite, low-bandwidth channel best for short exchanges.

SMS is included on Growth and above. Growth+

Step 1: buy a Twilio phone number

If you don't already have one:

  1. Sign in to Twilio at twilio.com/console.
  2. Navigate to Phone Numbers > Manage > Buy a Number.
  3. Pick the country and search for numbers with SMS capability enabled.
  4. Buy the number. US numbers cost about $1 per month plus per-message fees.

For high-volume use cases, buy a short code instead of a long code. Short codes have higher throughput limits and better deliverability but cost about $1,000 per month plus a 6 to 12 week approval process.

Step 2: connect to AskVault

  1. In Twilio Console, copy your Account SID and Auth Token from the home page.
  2. In AskVault, open Channels > SMS.
  3. In the Account step, enter your Twilio Account SID and Auth Token.
  4. In the Get a Number step, reuse the number you bought, or buy a new one, and finish the setup.

SMS runs on your own Twilio account: the number and every text are billed to you by Twilio, not by AskVault. If your workspace already has a WhatsApp number bought through Twilio, setup offers to add SMS to it instead of buying another; Twilio's shared WhatsApp test (sandbox) number can't carry SMS, because it isn't yours.

AskVault auto-configures the Twilio webhook URL on the number so inbound messages route to AskVault. Test it: send an SMS from your personal phone to your new Twilio number. The AI agent should reply shortly.

Step 3: A2P 10DLC for US numbers

If your Twilio number is US-based, you must complete A2P 10DLC (Application-to-Person 10-Digit Long Code) registration before sending production traffic. Without it, US carriers filter your messages and customers get nothing.

The registration process:

  1. Register your brand. In Twilio Console, Messaging > Regulatory Compliance > A2P 10DLC > Brands. Provide your company legal name, EIN, address, and a few details about the business. Twilio submits the brand for verification. Takes 1 to 3 business days.
  2. Create a campaign. Once the brand is verified, create a campaign that describes how you'll use the number (e.g., "Customer support replies and account notifications"). Campaign approval takes 1 to 5 business days.
  3. Associate the number with the campaign. Once approved, link your Twilio number to the campaign.

Twilio charges a one-time $40 brand registration fee plus a $10 per-campaign monthly fee. After this you can send production SMS without filtering.

International numbers don't need A2P 10DLC, but each country has its own rules. Twilio's docs cover the per-country requirements.

Business hours

Under Auto-replies, hours & keywords you can set opening hours and an after-hours reply. Choose your timezone by its standard name, for example America/New_York. A timezone AskVault doesn't recognise (such as "Pacific Time") can't be applied, and your hours would run on UTC instead.

Step 4: opt-in compliance

SMS regulations require explicit opt-in before you send messages. Three valid sources:

  • Web form checkbox at signup: "Yes, send me text-message updates."
  • Customer texts in first. When a customer initiates the conversation, replies don't require separate opt-in.
  • Verbal opt-in captured in your CRM with date and time.

Don't import contact lists and bulk-message. Carriers will block your number and Twilio may suspend your account.

For every outbound message you send, include Reply STOP to opt out in the first message of a session. Twilio handles STOP and HELP keywords automatically (customer texts STOP, future messages are blocked).

Pricing

US SMS via Twilio costs about $0.0079 per outbound message and $0.0079 per inbound, plus carrier surcharges (about $0.003 per message). India SMS is roughly $0.027 per message but rules and pricing vary by carrier.

Each successful AI-reply on SMS counts as 1 message against your AskVault plan's monthly quota.

Common pitfalls

Messages don't deliver to customers. Most commonly A2P 10DLC isn't registered for US numbers. Check Twilio Console > Messaging > Logs for error code 30007 (filtered).

Webhook delivery fails. Check Twilio Console > Phone Numbers > [your number] > Webhook URL. It should point to AskVault's API endpoint. If you accidentally edited it, re-save in AskVault to re-set it.

Customer texts STOP but bot keeps replying. Twilio handles STOP at the carrier level; AskVault won't see further messages from that number. Confirm the customer isn't messaging from a different number.

Bot replies are truncated. SMS messages have a 160-character limit (or 70 for non-Latin scripts). Twilio auto-segments longer messages, but each segment costs separately. To keep replies short, add a line to your system prompt such as "Keep SMS answers to two sentences."

FAQ

Can the bot send images?

Not yet. SMS replies are text only. Sending pictures by MMS is rolling out and is not available today.

What's the difference between SMS and WhatsApp?

SMS works on every phone, no app needed. WhatsApp requires the app but supports rich media, conversation context, and message templates for outbound campaigns. For India and Southeast Asia, WhatsApp is the dominant channel. For the US, SMS is universal.

Does the bot work with toll-free numbers?

Yes, but US toll-free numbers have their own verification process (separate from A2P 10DLC). Register the toll-free number with Twilio's Toll-Free Verification program. Takes about 2 to 4 weeks.

Can I use a non-Twilio SMS provider?

Not natively today. Twilio is the only SMS provider we support out of the box. For custom SMS providers, use the REST API channel to route messages programmatically.

How do I handle inbound spam?

Twilio has built-in spam detection that blocks obvious junk before it reaches AskVault. For additional filtering (e.g., a customer who keeps sending nonsense), tell your team to ignore the thread. AskVault does not have a block button for SMS senders today.

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