iMessage vs SMS for agents

iMessage is Apple's own messaging network — the blue bubbles — and it runs over the internet between Apple devices, end-to-end encrypted, with typing indicators, read receipts, tapbacks, threaded replies, edit and unsend, and full-resolution media. SMS is a carrier text protocol from the 1990s: green bubbles, 160 characters per segment, no encryption, and none of those conversational signals. For an AI agent the practical difference is that iMessage can hold a conversation and SMS can only deliver a notification.

Yes, through an iMessage API. Linq gives you dedicated lines and an API that sends and receives native iMessage — including group chats, typing indicators, reactions, and full-resolution media — so an agent you build can talk to customers in the same thread they use with family and friends. It is the only SOC 2 Type II certified iMessage API.

Not for iMessage. A2P 10DLC brand registration, per-campaign vetting, and the monthly campaign fees that come with them are requirements of the carrier SMS network, and iMessage does not run on it. That removes the one-to-four-week registration wait before your first production message, the per-campaign approval step for every new use case, and the carrier-assigned trust score that caps how fast you can send. Messages that fall back to RCS or SMS do travel over the carrier network, where the usual carrier rules apply — that is a property of those channels, not of iMessage.

Yes. iMessage is end-to-end encrypted, while SMS travels as plaintext across carrier networks and is commonly handled by three or more carriers on the way to the recipient. On Linq, message content is encrypted and inaccessible even to Linq, and the platform is SOC 2 Type I and Type II certified — the only iMessage API that is.

SMS is metered: you pay per 160-character segment, plus carrier pass-through fees of roughly $0.002 to $0.004 per message that are raised annually, plus brand and per-campaign registration fees. A single emoji re-encodes the whole message and cuts the segment down to 70 characters, so a conversational message can cost two to three times what you expected. Linq prices per line instead of per message, so the cost of a long, chatty, emoji-heavy agent conversation is the same as the cost of a short one.

Linq sends iMessage first and falls back to RCS or SMS automatically for Android and non-Apple devices, so you build against one API and reach everyone. iMessage covers the majority of US smartphones; the fallback covers the rest without a second integration.

Yes, and all three are native rather than emulated. iMessage group threads support adding and removing participants and updating the name and icon, and an agent can participate in one. Typing indicators, read receipts, emoji and sticker tapbacks, threaded replies, edit and unsend, and 11 screen and 4 bubble message effects are all part of the protocol. None of them exist in SMS — group MMS degrades on mixed-platform threads, and read receipts are inconsistent at best.

For one-time passcodes and two-factor codes, which are tied to the SIM and are what users expect; for masked-number communications, where proxy numbers connect two parties without revealing either; and for delivery to a phone with no data connection, since SMS rides the carrier control channel. SMS is also universal across every device. Those are real advantages, and they are why Linq routes iMessage first with RCS and SMS fallback rather than treating the channels as an either-or choice.

Minutes. You can sign up for a sandbox, get API keys, and send a real message without talking to sales — there is no brand registration, campaign approval, or carrier vetting in front of you. Getting an A2P SMS campaign live typically takes one to four weeks of brand and per-campaign registration first.