Guides
How messaging agents work underneath, which channels you can reach, what the rules are, and what it costs. Where a guide cites a number about this market, it is drawn from the 33 agents in this directory rather than from anyone’s marketing.
- A2P 10DLC registration: what it costs and how long it takes
If your agent sends SMS from a US 10-digit number you must register the brand and the campaign. Here is what that costs, what it saves, and what happens if you skip it.
Updated 2026-09-06
- Apple Messages for Business, and why you probably cannot use it
The only route into iMessage that Apple sanctions, what it requires, why it is closed to almost everyone, and what that means for the rest of the market.
Updated 2026-09-06
- What Apple's terms say about all this
Almost every iMessage agent runs on infrastructure Apple did not sanction. What Apple's published terms say, what Apple has actually done, and what nobody knows.
Updated 2026-09-06
- Blue bubble or green: what actually changes for an agent
The difference between iMessage and SMS fallback is not cosmetic. It changes what your agent can do, what it costs and whether it works at all.
Updated 2026-09-06
- How messaging agents get their second user
Onboarding friction decides which agents spread and which stall. Here is what 33 shipping agents actually require of a new user.
Updated 2026-09-06
- How to build an iMessage agent in 2026
Apple publishes no general iMessage API. Here are the three routes that exist, what each costs, and what you take on with each.
Updated 2026-09-06
- iMessage vs SMS vs WhatsApp vs RCS for AI agents
Which messaging channel to build an agent on, compared by reach, access, cost, rich features and what the products shipping today actually chose.
Updated 2026-09-06
- Who publishes llms.txt, and what they put in it
17 of 31 messaging agent sites serve a real llms.txt, against roughly 1 percent of the web. Here is who, what is inside, and how to verify a claim like this.
Updated 2026-09-06
- What it costs to run a messaging agent
The real cost of running an AI agent on iMessage, SMS, WhatsApp or RCS, infrastructure, per-message fees, registration, and what the products in this directory charge.
Updated 2026-09-06
- Who actually carries the messages
Eight of 33 messaging agents say who runs their iMessage infrastructure. All eight named the same company. Here is the evidence and the method.
Updated 2026-09-06
- Who you are allowed to message
Consent, bot disclosure, and the people in a group thread who never agreed to anything. What the rules say, with the sources, for anyone building an agent that texts.
Updated 2026-09-06