# A2P vs bulk SMS — what's the difference?

> A2P SMS and bulk SMS overlap but are not the same thing: A2P (application-to-person) describes who sends a message — a software application reaching a person with an OTP, alert, or notification — while bulk SMS describes how you send — one message pushed to many recipients at once, almost always for marketing. All bulk SMS is A2P, but not all A2P is bulk.

- Canonical URL: https://www.broadnet.me/answers/a2p-vs-bulk-sms
- Language: en
- Last reviewed: 2026-09-24
- Publisher: BroadNet (https://www.broadnet.me)

## Category vs sending pattern

A2P is a traffic category defined by the sender: any message a software application submits to reach a person is A2P, whether it goes to one recipient or a million. Bulk SMS is a sending pattern defined by fan-out: one piece of content delivered to a large recipient list in a single campaign. A single transactional OTP to one number is A2P but not bulk; a promotional blast to 500,000 numbers is both A2P and bulk.

- A2P = who sent it (an application, not a human on a handset).
- Bulk = how many at once (one message, many recipients).
- Every bulk send is A2P; not every A2P message is bulk.
- OTPs and one-off alerts are A2P but individual, not bulk.

## Where they typically diverge

Bulk SMS is overwhelmingly marketing: newsletters, offers, and announcements to an opted-in audience. Non-bulk A2P is dominated by transactional and authentication traffic: OTPs, delivery updates, appointment reminders. That difference in purpose pulls in different rules — bulk marketing needs explicit opt-in and a working opt-out, while individual transactional A2P a user requested can usually be sent without marketing consent.

- Bulk: marketing campaigns to an opted-in list.
- Individual A2P: OTPs, transactional alerts, reminders.
- Bulk marketing requires opt-in + opt-out; transactional generally does not.
- See sms-marketing-vs-transactional for the consent line.

## Routing and sender ID are the same underneath

Both bulk and non-bulk A2P ride the same sanctioned, operator-direct routes and carry a registered sender ID — sending either over a P2P grey route to save money gets it blocked by the destination operator's SMS firewall. On BroadNet's gateway you send both the same way: an individual OTP via a single POST /sms/sendSms call, a bulk campaign by uploading a recipient file to the /sms/sendbulk endpoint.

- Both use operator-direct A2P routes and a registered sender ID.
- Grey-route shortcuts are blocked regardless of volume.
- Single send: one POST /sms/sendSms call.
- Bulk: upload a recipient file to POST /sms/sendbulk.

## A2P SMS vs bulk SMS at a glance

|  | A2P SMS | Bulk SMS |
|---|---|---|
| What it describes | The sender (an application) | The fan-out (one message, many recipients) |
| Typical volume | One to millions | Large recipient lists |
| Primary use | OTP, alerts, transactional, marketing | Marketing campaigns and announcements |
| Consent | Depends on content (transactional vs marketing) | Explicit opt-in + opt-out required |
| Sender ID | Registered alphanumeric / sender ID | Registered alphanumeric / sender ID |
| Routing | Operator-direct A2P route | Operator-direct A2P route |

## Frequently asked questions

### Is all bulk SMS also A2P?

Yes. Bulk SMS is sent by an application to many recipients, which is application-to-person by definition. Bulk is a subset of A2P — the high-fan-out, usually-marketing subset.

### Is an OTP bulk SMS?

No. An OTP is A2P (sent by your application) but individual, not bulk — it goes to a single recipient in response to a specific event, not as a one-to-many campaign.

### Do bulk and non-bulk A2P cost the same per message?

They use the same operator-direct routes, so the per-message termination cost is the same for a given destination. Volume tiers can lower the unit price on large bulk sends, but the route and sender-ID handling are identical.

### How do I send a bulk campaign on BroadNet?

Upload a recipient file (CSV or TXT) to POST /sms/sendbulk as multipart form data, with a bulkRequest JSON part carrying senderId, message, messageType and campaignName. The response returns a bulkSessionId plus total, valid, invalid and duplicate counts, and you can pause, resume or abort the batch while it runs.

## Related

- [What is A2P SMS?](https://www.broadnet.me/answers/what-is-a2p-sms)
- [SMS marketing vs transactional](https://www.broadnet.me/answers/sms-marketing-vs-transactional)
- [A2P vs P2P SMS](https://www.broadnet.me/answers/a2p-vs-p2p-sms)
- [All answers](https://www.broadnet.me/answers)
- [What is A2P SMS?](https://www.broadnet.me/answers/what-is-a2p-sms)
- [SMS marketing vs transactional SMS — what's the difference?](https://www.broadnet.me/answers/sms-marketing-vs-transactional)
- [A2P vs P2P SMS — what's the difference?](https://www.broadnet.me/answers/a2p-vs-p2p-sms)
- [What is bulk messaging?](https://www.broadnet.me/answers/what-is-bulk-messaging)
- [A2P SMS](https://www.broadnet.me/products/a2p-sms)
- [Bulk SMS](https://www.broadnet.me/products/bulk-sms)