The two pricing models in this space are not shaped the same way, which makes the comparison harder than it looks. SMS bills per message segment. iMessage providers bill per phone line, flat, with the messages included. Comparing a fraction of a cent to $99 a month requires knowing your own volume before either number means anything.
The SMS invoice has more lines than you think
A quoted SMS rate is rarely what you pay. The bill assembles from several places:
- Per-segment cost, not per message. SMS breaks every 160 characters, or every 70 if you use a single emoji, which silently switches the whole message to a different encoding. A three-sentence reminder with a link and an emoji can bill as three segments.
- Carrier pass-through fees. Charged on top of the provider's rate, and they change without much notice.
- A2P 10DLC registration. A brand fee, a campaign fee, and a monthly campaign charge — before you send anything.
- MMS for photos, billed at several times the SMS rate, and the photo arrives compressed anyway.
- The number itself, monthly.
The cost that never appears on the invoice
Registration takes days to weeks. For a seasonal business or one testing a channel, that lead time is a real cost — it is the difference between trying something in March and trying it in April.
The iMessage invoice is one line
Per-line pricing means the bill is the bill. From the current published pricing on the two providers covered here:
| Provider | Entry tier | Production tier | Metered? |
|---|---|---|---|
| Miss Blue | $0 sandbox | $78/mo shared, $198/mo dedicated | No |
| Sendblue | $0 sandbox | $100/mo per dedicated line | Inbound contact cap |
Miss Blue lists promotional rates of $39 and $99 respectively. Both providers include a free sandbox. Full detail, including what each tier actually contains, is on the provider comparison.
Check these before you budget
Third-party comparison articles in this category are mostly published by the vendors themselves and quote wildly different figures for competitors — we have seen Sendblue quoted at ten times its own published price. Use each vendor's own pricing page as the only authority.
Where the crossover sits
Take a clinic sending appointment confirmations and reminders — two messages per appointment, four hundred appointments a month, so eight hundred messages. Assume the reminder runs long enough to bill as two SMS segments, which is typical once you include a link.
| SMS | iMessage line | |
|---|---|---|
| Message volume | 800 messages ≈ 1,400 segments | 800 messages |
| Variable cost | Segments × rate + carrier fees | $0 |
| Fixed cost | Number + campaign registration monthly | $99–198/mo |
| Setup delay | Days to weeks for 10DLC | Same day |
| Photos | Billed as MMS, arrive compressed | Included, full quality |
| Cost of one more message | Another segment | Nothing |
At that volume the two land in roughly the same range. But the shapes differ in a way that matters more than the total: on SMS, every additional message costs money, so you send only what you must. On a line, the marginal message is free, so you send what is *useful*. That difference in behavior is where most of the goodwill in this channel gets generated — and it does not show up in a cost comparison at all.
The cost of a message nobody read
The comparison above assumes both messages do the same work. They do not. A reminder that gets ignored costs you the no-show, and a no-show costs a full appointment slot — which for most service businesses is between $80 and several hundred dollars of unrecoverable revenue.
Against that, the gap between a $30 SMS bill and a $99 line is noise. One prevented no-show a month covers the difference. Two makes the decision obvious. This is why the reply rate matters more than the send cost — but it is also why you must measure it rather than assume it.
When SMS is genuinely the right answer
- Your list skews Android. You would be paying for a line that reaches a minority of your customers.
- You send at high volume with low value per message. Per-line caps and fair-use limits start to bind, and metered pricing may work out cheaper.
- Delivery is contractual. SMS has decades of formal delivery guarantees behind it.
- You already have SMS working well. A channel that produces results is not a problem to solve.
The most common good answer is not either/or. Run iMessage where it lands and fall back to SMS where it does not — Sendblue does this automatically, which is a genuine reason to prefer it if your list is mixed. Compare the fallback behaviour.
How to actually decide
Four numbers, then a decision
- What share of your customer list is on iPhone?
- How many messages do you send a month, and how many segments is that really?
- What is one prevented no-show, or one recovered cart, worth to you?
- What are you paying for SMS today, all fees included?
Two adjacent comparisons worth reading if you are still narrowing the field: iMessage API vs Twilio, since Twilio is where most people start, and iMessage vs WhatsApp Business if any of your customers are outside North America.
If iPhone share is above roughly 60% and one saved appointment covers the line, the arithmetic works before you factor in any engagement lift at all. Everything above that is upside — and you should measure it rather than trust it.