One REST surface
SMS, MMS, RCS, AI voice agents, call announcements, and number intelligence are reached through one REST API with JSON payloads rather than separate products you assemble.
Detail: /integrations/apiDeveloper hub
Messaging infrastructure for the product you already built
You built the CRM. You built the platform. What you did not plan to build is a messaging operation: sender registration, carrier reviews, opt-out handling, delivery events, and the routing decisions behind every send. Tells gives your product one REST surface for that, and a team that owns the telecom side of it.
Tells is a business messaging platform that product teams integrate through one OAuth2 authenticated REST API. The same surface covers SMS and MMS, RCS with automatic SMS fallback, AI SMS and voice agents, call announcements, and number intelligence, with webhooks for delivery, inbound messages, replies, and opt-outs across United States and Canada carrier routes. Sender registration and program monitoring are performed by the Tells team, so the integration work your engineers own stays on your side of the boundary.
Directory
Pick the path that matches what you are building
Four routes into the same platform, plus the reference material. They are deliberately different pages, not the same page with different headings.
Primary path
SMS API for CRMs
You built or operate a CRM and your customers keep asking for texting inside the record. Architecture, inbound and outbound flows, webhooks, and the compliance work that comes with sending on behalf of your customers.
Read the CRM integration guide → Product teamsAdd SMS to an app
You have a SaaS product, an internal platform, or a workflow tool and messaging is now a feature request. Integration flow, webhook events, identity and number checks, and the path from SMS to RCS and voice.
Read the app integration guide → Platform detailEnterprise SMS API
The full platform view of the REST surface: what you can send, what you can listen for, how authentication works, and which use cases the enterprise API is built around.
See the API page → EvaluatingTells vs Twilio for developers
A factual look at the decision dimensions that actually differ, plus a vendor neutral evaluation checklist you can run against any messaging provider, including this one.
Open the evaluation → ReferenceDeveloper documentation
The public overview of the API surface: quick start, authentication model, SMS and MMS, RCS, voice and AI agents, number intelligence, and webhooks. The full reference arrives with account access.
Open the docs overview → PrebuiltExisting integrations
If your stack already runs on Salesforce, HubSpot, HighLevel, Shopify, or Zapier, there may be nothing to build. Start with the prebuilt connector before writing an integration.
Browse integrations →Platform surface
What the REST surface covers
Every capability below is documented on a live Tells product page. Each card links to the page it came from so you can check it rather than take our word for it.
OAuth2 authentication
The API uses OAuth2 bearer authentication. Credentials are issued during account onboarding and scoped to your workspace, and they are meant to stay server side.
Detail: /docsSMS and MMS at program volume
Programmatic SMS and MMS across US and Canada carrier routes with 10DLC, short code, and toll-free sender support, automated STOP and HELP handling, and per-message carrier delivery receipts.
Detail: /docsWebhooks instead of polling
Event callbacks cover carrier acceptance, delivery, inbound messages, replies, call completions, and opt-out events, so your database stays current without a polling loop.
Detail: /integrations/apiRCS with automatic SMS fallback
Verified brand sender RCS with rich cards, carousels, and quick replies, falling back to SMS automatically on devices that cannot receive it. Tells handles the Google verification submission.
Detail: /docsAI voice agents and call announcements
AI SMS and voice agents share conversation context, escalate to a human with the full transcript, and branded SMS call announcements can be sent ahead of an outbound dial through the same REST surface.
Detail: /docsNumber intelligence in the send path
Carrier and line type, CNAM, and a 0 to 100 activity score are available in real time and can be used inside the send path for routing and suppression decisions.
Detail: /solutions/number-intelligenceUS and Canada carrier coverage
Coverage is focused on United States and Canada carrier routes, with sender registration and program monitoring performed by the Tells team rather than left in your backlog.
Detail: /solutions/high-volume-smsIntegration path
How teams get from scoping to a live program
The same five steps whether you are embedding messaging in a CRM or adding it to a SaaS product. The details differ; the sequence does not.
- 01
Scope the program
Volumes, sender types, who the sender legally is, which countries, and which events should trigger a message. This shapes registration and routing before any code is written.
- 02
Get credentials
Onboarding issues workspace-scoped OAuth2 credentials, sets up your environment, and walks you through a first send so the plumbing is proven before you build on it.
- 03
Wire the send path
Your service calls the REST API to send. Number intelligence can run inside that path so routing and suppression decisions happen before the message leaves.
- 04
Wire the listen path
Point webhook endpoints at your service for carrier acceptance, delivery, inbound messages, replies, call completions, and opt-out events, and reconcile them against your own records.
- 05
Expand the channel
Once SMS is live, RCS with automatic SMS fallback, AI voice agents, and call announcements attach to the same relationship and the same REST surface.
Access model
How access works
Tells API access is provisioned per account. The complete endpoint reference, request and response schemas, SDKs, Postman collection, sandbox environment, rate limits, and status codes are provided with account credentials during onboarding rather than published publicly. The public overview of what the platform supports lives on the developer documentation page.
- Access starts with a short scoping call, not a signup form
- Credentials, environment setup, and a guided first send come with onboarding
- The full reference is account gated, so plan your integration spike after access
Carrier and registry approval decisions remain outside any provider control, including ours.
Plain English
Terms that come up in every messaging integration
Short, vendor neutral definitions. If a provider explains these differently, ask why.
- SMS API
- An SMS API is an HTTP interface that lets your software send and receive text messages programmatically instead of through a console. Your application authenticates, posts a message with a destination number and body, and receives status updates as callbacks.
- Webhook
- A webhook is an HTTP request the messaging platform sends to a URL you own when something happens, such as a carrier accepting a message, a recipient replying, or a recipient opting out. Webhooks replace polling: your system learns about the event when it occurs.
- A2P 10DLC
- A2P 10DLC is the United States framework for application to person messaging sent from ten digit long code numbers. Brands and campaigns are registered with The Campaign Registry, and carriers use that registration to decide how traffic is treated.
- RCS Business Messaging
- RCS Business Messaging is a richer successor to SMS that supports verified brand senders, cards, carousels, and quick replies on supported devices. Well built RCS programs fall back to SMS automatically when a device cannot receive it.
- Number intelligence
- Number intelligence is real time metadata about a phone number, such as its carrier, its line type, the caller name on record, and how active it is. Used inside the send path, it lets a system decide whether to send, how to route, or when to suppress.
FAQ
Developer questions we get before access
What can a product team build on the Tells API?
Custom application integrations, internal tools and dashboards, multi tenant SaaS platforms, white label messaging, workflow automation, real time event processing, custom analytics, and integrations with legacy systems. The API covers SMS and MMS, RCS, AI voice agents, call announcements, and number intelligence over REST.
How do I get API access?
Access is provisioned per account rather than through a public signup. Tell the team what you are building on a short call, and onboarding includes OAuth2 credentials scoped to your workspace, environment setup, and a guided first send. Developer onboarding by email is also available.
Is the full API reference public?
No. The developer documentation page is a public overview of what the platform supports. The complete endpoint reference, request and response schemas, SDKs, Postman collection, sandbox environment, rate limits, and status codes are provided with account credentials during onboarding.
Which countries does Tells cover?
Tells is focused on United States and Canada carrier routes. If your program needs coverage outside North America, raise that in scoping before you plan an integration.
Who handles 10DLC registration for a platform sending on behalf of its customers?
The Tells team prepares, submits, and tracks brand and campaign filings and works the carrier review follow ups. Your side of the boundary is supplying accurate brand and use case information and holding consent records for the recipients you message. Carrier and registry approval decisions remain outside any provider control, including ours.
Talk through the integration before you build it
API access is provisioned per account, so the shortest path in is a scoping conversation with the team that would run the messaging side. Your details carry straight into scheduling; there is no second form.
Prefer email? Developer onboarding runs through dave@tells.co.