A2P Messaging API

The A2P Messaging API is how your code sends messages through Instasent. It connects your application to carrier networks, delivering to handsets in 200+ countries, and covers everything around the send: single or batched sending, DLRs and inbound, message history, HLR lookups, price profiles and account balance. Today it sends SMS; RCS and WhatsApp are coming soon.

Two transports expose the same underlying pipeline. Pick the one that fits your stack — most teams start with HTTP and only move to SMPP when volume or session-state requirements justify it.

What you can do

• Send SMS, one at a time — POST /sms for triggered traffic (OTPs, alerts, receipts, notifications).
• Send SMS in bulk — POST /sms/bulk takes a collection of messages in a single request. This is the endpoint for API-driven campaigns, marketing fan-outs and any high-volume dispatch. Customers including marketing agencies run entire campaigns on top of it.
• Receive delivery reports (DLRs) as carriers report status back through the chain, pushed to your webhook in real time.
• Accept inbound messages when the account has two-way enabled.
• Query message history and per-message status — GET /sms, GET /sms/{id}.
• Run HLR / number lookups — POST /lookup, GET /lookup/{id} and GET /lookup to check handset presence and routing before sending.
• Read account balance — GET /organization/account.
• Read price profiles — GET /sms/price-profile/me/countries and GET /lookup/price-profile/me/countries for per-country pricing.

When to use this API

Reach for A2P Messaging whenever your code needs to send — one message or many — without asking Instasent to manage the recipient audience. Typical workloads:

• User-triggered messages — OTPs, password resets, receipts, shipping notifications. One message per event, delivered in seconds, via POST /sms.
• API-driven campaigns and bulk dispatch — marketing sends, notification fan-outs, anything that fires many messages in one go. Use POST /sms/bulk.
• Wholesale SMS over SMPP — aggregators, messaging platforms and resellers pushing their own traffic through Instasent. SMPP gives carrier-grade throughput over persistent sessions; HTTP also works at moderate rates.
• Pre-send validation and pricing — HLR lookup and price profiles to route and cost-check before dispatch.

If you need Instasent to own the audience, personalization, segmentation and attribution, use the Product API instead — it delegates delivery to this one but adds the customer-data layer on top. The A2P Messaging API is the right pick when the caller already manages its recipient list and just needs to send.

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