Integrations / Business phone systems and carriers

Use AssistCall with Twilio

Keep your Twilio number. Forward it to AssistCall when you're busy, don't pick up or after hours, and every call gets answered, booked or turned into a message, with a summary by email.

Twilio: Developer platform for phone numbers, calls and texts, which businesses and their developers use to build their own phone lines and call flows.

Connects

Example call

A caller dials a clinic's Twilio number at lunchtime. The Studio flow rings the front desk for 20 seconds, then dials AssistCall, which books the visit, and a Zap texts the patient the confirmation from the clinic's Twilio number.

• Point your Twilio number at a Studio flow that dials your own phone first and then dials your AssistCall number if nobody answers, or straight to AssistCall after hours.
• When AssistCall books an appointment, Zapier's Twilio Send SMS action (or Make or n8n) texts the caller a confirmation from your Twilio number.
• During a call, the receptionist looks up the caller's number with Twilio's Lookup API, using your API key in a Basic auth header, to check whether it is a mobile line before offering a text.

How it connects

• Call forwarding: Forward your business line to AssistCall when busy, after hours or always. Works with any carrier.
• Live API actions: During the call, the receptionist calls the app's API with your key to look up or create records.
• Webhook: Signed JSON for every call, message and booking, sent to any HTTPS URL you choose.
• Zapier: Send AssistCall events to a Zap (Webhooks by Zapier, Catch Hook), then use the app's Zapier actions. Needs a paid Zapier plan.
• Make: Start a Make scenario with a custom webhook and use the app's Make modules.
• n8n: Start an n8n workflow with a webhook node, then call the app with its node or an HTTP request.

About Twilio's API

• Self-serve API: you can create a key in your account
• Style: REST, TwiML, Studio flows and Functions
• Authentication: HTTP Basic auth with an API key SID and secret (or Account SID and Auth Token); keys work until you revoke them
• On Zapier: yes. On Make: yes.

Anyone can create a Twilio account and API keys, and a Basic auth header doesn't expire, so AssistCall can call Twilio live. Most Twilio write endpoints, such as sending a text, take form-encoded bodies rather than JSON, so the clean live call is a GET (for example Twilio's Lookup v2 API, where line type data is billed per lookup); for texting, use Zapier's Send SMS action, Make's Create a Message module, n8n's Twilio node, or a Twilio Function your developer writes. Forwarding: a TwiML Bin with a Dial verb, or a Studio flow with a Connect Call To widget, sends calls to your AssistCall number. Connect Call To has a timeout (default 30 seconds), and its Connected Call Ended transition can lead to a second dial to AssistCall for unanswered calls.

Not included: no one-click Twilio app, no listing in Twilio's marketplace, no two-way sync, and no partnership with Twilio Inc..

Researched by the AssistCall team and checked against Twilio Inc.'s public pages on October 24, 2026. Twilio is a trademark of Twilio Inc.. AssistCall is an independent product of Starling Global LLC and is not affiliated with, endorsed by, sponsored by or approved by Twilio Inc..

More Business phone systems and carriers integrations

• AT&T Business: AT&T's business wireless, fiber and phone service, which many small businesses use for the mobile or landline number printed on their trucks, cards and listings.
• Comcast Business: Comcast's internet and business phone service (Business Voice and VoiceEdge) for offices, shops and restaurants in its cable footprint.
• RingCentral: Cloud business phone system (RingEX) with calling, texting, video and team chat in one app, used by small offices up to large companies.
• Spectrum Business: Charter's internet, mobile and business phone service (Spectrum Business Voice) for small businesses in Spectrum service areas.
• T-Mobile for Business: T-Mobile's wireless and internet service for small businesses, often the owner's mobile number doubling as the business line.
• Verizon Business: Verizon's business wireless, internet and phone service, used by many small businesses whose main number is an owner's or staff member's Verizon mobile line.

All product and company names in this directory are trademarks or registered trademarks of their respective owners, used only to identify systems AssistCall can send call information to or receive information from. Their use does not imply any affiliation with or endorsement by their owners. AssistCall connects using signed webhooks, the business's own API keys, automation platforms (Zapier, Make, n8n) the business sets up in its own account, and call forwarding. AssistCall does not provide one-click connectors, marketplace apps, certifications or two-way record or calendar sync, and does not sign HIPAA business associate agreements. Vendor features, plans and API access can change; information last checked October 24, 2026.