Most businesses that text do two kinds of messaging. Some texts are personal: a rep typing "Running 10 minutes late, see you at 2" to one customer. Others are automated: appointment reminders, order updates, a promo sent to a list. Many teams assume the first kind is "P2P" and needs no paperwork, while only the second kind is "A2P" and has to be registered.
US carriers don't draw the line there. The labels describe how a message is sent and who sends it, not how personal it sounds. This post defines both terms, explains which rules apply to each, and covers what happens to texts that end up on the wrong side of the line.
What A2P and P2P actually mean
P2P (person-to-person) is one human texting another from a phone: you text your sister, your sister texts back. The volume is low, the conversation goes both ways, and the sender is a person on a consumer phone plan.
A2P (application-to-person) is any text that software sends on behalf of a business. The software might be a CRM, a scheduling tool, an ecommerce platform, a texting app or your own code calling an API. A2P traffic can be automated (a reminder fires 24 hours before an appointment) or manual (a staff member types a reply in a shared inbox). If it travels through a business messaging platform on a business number, carriers count it as A2P.
That second point trips people up. A reply your front desk types by hand in a web inbox still comes from a business sender through an application. To the carrier, it is A2P traffic.
Why business texting is almost always A2P in the US
US carriers created the 10DLC system (10-digit long code) so businesses texting from ordinary local numbers would register who they are and what they send. Before 10DLC, a lot of business traffic went out on long codes as if it were consumer P2P traffic. Carriers could not tell a dentist's reminders from a spammer's list, so they filtered both.
Today the practical rule is simple. If a business sends texts from a number provisioned through a messaging provider, that traffic needs a registered brand and campaign, whether a human or a workflow pressed send. The narrow P2P case is an employee texting from their own personal phone on a consumer plan. Even that has limits: carriers watch consumer lines for business-style volume, and they can flag a personal number that suddenly texts hundreds of people.
For a longer answer on who has to register, see Is A2P 10DLC required to send business SMS?.
Which rules apply to each
| P2P (personal phone) | A2P (business platform, 10DLC) | |
|---|---|---|
| Who sends | A person on a consumer line | Software on behalf of a business, automated or typed by staff |
| Registration | None | Brand + campaign registration with the carriers |
| Typical volume | Low, conversational | Anything from a few texts to large campaigns |
| Throughput | Not metered for business use | Per-second and daily caps set by campaign and brand trust |
| Opt-out handling | Informal | STOP must be honored and kept |
| Consent | Social norms | Opt-in required, and the sender keeps the proof |
| TCPA exposure | Rarely relevant | Real: statutory damages are often cited at $500 to $1,500 per text |
| Carrier filtering | Spam filters on content | Content filters, plus heavy filtering of unregistered traffic |
The TCPA and consent rules attach to the business purpose of a message, not to the sending technology. A marketing text to someone who never opted in is a problem whether it came from a platform or a rep's personal phone. Moving business texting onto personal phones to avoid registration doesn't remove the consent obligation. It only removes your audit trail.
What happens to unregistered A2P traffic
Carriers filter unregistered business traffic on 10DLC numbers. The symptoms are usually quiet:
- Messages show "sent" in your tool but never arrive.
- Delivery works on one carrier and fails on another.
- Links get stripped, or messages with links are dropped.
- A number that worked last month starts failing as volume grows.
Registration also sets your speed limits. A fresh standard campaign without vetting typically gets about 1 to 4 segments per second. On T-Mobile, the daily cap for a brand depends on its trust score, with the lowest tier around 2,000 messages a day and higher tiers at roughly 10,000, 40,000, 100,000 and 200,000. AT&T throttles per second and per minute instead of setting a hard daily cap. These are approximations, because carriers don't publish an official rate card.
Registration is necessary, but it doesn't guarantee delivery. Content can still get filtered after approval. Campaign approved but messages still get filtered covers that layer.
Mixing personal-style and automated texts: one campaign or two
Most businesses sending mixed traffic need one registered brand and one campaign whose use case matches what they actually send. Here is a common pattern:
- Conversational replies typed by staff (scheduling questions, quotes, follow-ups)
- Transactional or informational automations (reminders, confirmations, delivery updates)
- Occasional marketing to opted-in contacts (seasonal offers, reactivation)
If all three go to the same opted-in customers, a mixed use case often fits. If one stream is very different, a second campaign can make sense. Examples include high-volume marketing next to time-sensitive codes, or a separate brand sending on your behalf. The cost of getting this wrong is real: a campaign registered for one purpose that carries another is a common cause of throttling and rejections. Matching use case to what you actually send walks through the choice.
Your sample messages and opt-in description should cover every type of text you plan to send, including the hand-typed replies. Reviewers compare what you registered against what they see on the wire.
Worked example: what a mixed month costs
This is an illustrative example with stated assumptions, not a customer's bill. A service business on Ready Standard sends one number's worth of traffic in a month:
- 2,000 appointment reminders, about 140 characters each with no emoji: 1 segment each, so 2,000 segments
- 300 staff-typed replies, averaging about 200 characters: 2 segments each (153 characters per segment once a text splits), so 600 segments
- 400 inbound customer replies, about 1 segment each: 400 segments. Received texts are billed like sent ones.
That totals 3,000 segments. On Standard, the cost is 3,000 × $0.0075 = $23, plus 3,000 × $0.0045 in carrier fee.
Ready's all-in prices per segment include the carrier fee but not screening: Scrub lists and Number validation, the two switches in Settings under Compliance, each add $0.003 per segment when switched on, shown as screening on your bill, and both are off by default. Unless you turn the opt-out footer off, the first text to each contact, and one again from time to time, also gets "Reply STOP to opt out" and your business name if the message does not already have them, so a text close to the segment limit can bill one more segment.
Registration adds a fixed monthly cost: $25/mo for registration and $2 per number, which is $27 a month here. There is no setup fee. The charge when you submit is the first month, $25.
A note on emoji: put one in those reminders and each 140-character text drops to the 70-character unicode limit and splits into 67-character parts, so it bills as 3 segments instead of 1. Ready swaps curly quotes, long dashes and ellipses for plain characters before sending, so those won't change your count. Emoji will.
Compliance pieces that apply to both kinds of messages
The safeguards that matter don't depend on whether a message feels personal or automated. In Ready they apply to every send from the account:
- STOP handling. An inbound STOP or UNSUBSCRIBE is honored, and the opt-out applies across campaigns. Opted-out numbers are refused up front and not charged.
- Quiet hours. Texts sent outside permitted hours in the recipient's area are held and sent later. You're charged only when a held text actually sends. Campaigns, drip campaigns and automations wait up to 24 hours for the window; a one-to-one or API text is held only if the window opens within 6 hours, otherwise it is refused and must be resent; a one-to-one reply to someone who texted you in the last 24 hours goes out at any hour.
- Attestation. Every campaign you send and every API send that attests consent records the sender's opt-in attestation: who sent it, to how many people and when. That builds an audit trail of your sends. It is not a per-contact consent record, so store each contact's opt-in time, wording and source page yourself.
- Optional scrubbing. You can screen known TCPA-litigator and DNC numbers before you send. This reduces risk but doesn't make you lawsuit-proof.
Compliance is still the sender's responsibility. These tools reduce exposure but don't replace consent. Use SMS for people who opted in or who contacted you first. Reach cold contacts by phone or mail.
If you build on the API, one-to-one and bulk sends both carry consent_attested, so your code states the opt-in either way. The request shapes are at docs.tryready.com/api/messages.
The practical takeaway
The A2P and P2P labels describe how a message is sent, not how friendly it sounds. If a business sends texts through software on a business number, that traffic is A2P, including replies your team types by hand. It needs a registered brand and a campaign that honestly describes everything you send. Skipping registration leads to filtering, and the failures are often silent.
If you're a solo operator texting a handful of clients from your own phone, none of this applies, and you don't need a platform. Once texting is part of how the business runs, register.
On Ready, the first 20 one-to-one texts are free, so use them before you register. An account can send up to 500 texts a month at its normal rate before registering. While your own registration is in review, an account that has bought a number sends on Ready's shared registration at the same rate. Most approvals take 2 to 7 days. Sending SMS without waiting on 10DLC explains that window, and pricing is at tryready.com/pricing. When you're ready, you can sign up here and register from inside the app.