iMessage Detection API — Check If a Number Has iMessage

Detect iMessage availability before sending. Route iPhone users to iMessage and Android users to SMS or RCS — all from a single API call.

Why Check Before Sending?

Not every phone number has iMessage. If you send an iMessage to an Android user, it won't arrive. Sendblue's number lookup API lets you check iMessage availability before sending, so you can route to the right channel every time.

Even though Sendblue handles auto-routing, proactive lookup gives you the data to customize your messaging strategy: different copy for iMessage vs SMS, different media approaches, and accurate campaign segmentation.

How It Works

Check a Phone Number

curl -X GET "https://api.sendblue.co/api/evaluate-service?number=%2B19998887777" \
  -H "sb-api-key-id: YOUR_API_KEY" \
  -H "sb-api-secret-key: YOUR_SECRET_KEY"

Response

{
  "number": "+19998887777",
  "is_imessage": true,
  "imessage_status": "active"
}

The response tells you whether the number has iMessage. Use this to decide your send strategy — iMessage with rich features, or SMS/RCS as a fallback.

Key Capabilities

Real-Time Detection

Get iMessage status in under a second. No cached or stale data — every lookup checks the current state.

Bulk Lookup

Check hundreds of numbers at once. Segment your contact list into iMessage and non-iMessage groups before sending.

Channel Routing

Use lookup results to route messages: iMessage for iPhone, RCS or SMS for Android. Maximize reach and deliverability.

List Hygiene

Identify invalid numbers and numbers that have switched devices. Keep your contact list clean and your delivery rates high.

Use Cases

Campaign Segmentation

Split your audience by channel before sending. Craft iMessage-specific content with media and effects, and simpler text for SMS recipients.

Lead Qualification

iPhone users often have different demographics and purchasing patterns. Use iMessage status as a data point in your lead scoring models.

Automated Routing

Build workflows that check each number and branch accordingly. iMessage gets typing indicators and rich media; SMS gets a clean text message.

Smart Routing Across Channels

Number lookup is the starting point for intelligent messaging. Once you know the channel, you can leverage the full suite of Sendblue features: typing indicators and read receipts for iMessage, RCS for Android, and rich media for both.

Track everything through webhooks, manage conversations in groups, and send contact cards to build trust. Build with the Sendblue API, CLI, or MCP server.

Know the channel before you send

iMessage detection in under a second. Free sandbox, no credit card required.

Get API Access

Frequently Asked Questions

How does number lookup work?

Send a phone number to the Sendblue lookup endpoint. Sendblue checks whether iMessage is registered for that number and returns the result. The check takes less than a second.

Can I check numbers in bulk?

Yes. Sendblue supports bulk number lookup. Send an array of phone numbers and get iMessage availability for each one. This is ideal for segmenting contact lists before a campaign.

What happens if I send to a number without checking first?

Sendblue automatically detects the best channel for each number. If iMessage is available, it sends via iMessage. If not, it falls back to RCS or SMS. Number lookup gives you this information proactively so you can customize your messaging strategy per channel.

Is the lookup result cached?

Sendblue returns real-time results. iMessage availability can change (e.g., when someone switches from iPhone to Android), so we recommend checking before time-sensitive campaigns.