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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 |