How to choose a CPaaS SMS provider: 10 questions to ask

To choose a CPaaS SMS provider, ask each vendor the same ten questions about registration, throughput, fees, opt-outs, scrubbing, support, sub-accounts, iMessage, test mode and pricing clarity, and get the answers in writing. The best CPaaS SMS provider for you is the one whose answers match the work your team would otherwise build and maintain yourselves, not the one with the lowest number on its pricing page.

Most evaluations of Twilio, Sinch, Plivo, Vonage and similar vendors start with a price spreadsheet and end with a surprise. The surprise is usually the carrier fee nobody modelled, or the registration queue that blocks launch for a week, or the sub-account architecture that turns out to be your problem to build. The questions below are written so you can paste them into an email to any vendor, Ready included. We make Ready, so where we describe our own answers we'll be specific, and we'll also say where a pure API provider is the better pick.

What "best cpaas sms provider" means depends on who you text for

Before the questions, settle one thing: are you texting your own customers, or are you a platform texting on behalf of your customers?

If you're a single business sending order updates and one-time passcodes, a raw CPaaS API is often the right tool. You register one brand and one or two campaigns, and your engineers wire up a send call.

If you're a CRM, a vertical SaaS product or any platform where each of your customers needs its own numbers, its own 10DLC registration and its own opt-out list, the job is different. You're now running a small telecom operation inside your product. Most of the questions below matter more in that second case.

Registration and throughput

1. Who does the 10DLC registration work, and how does it fail?

Every US business texting from a 10-digit number needs a registered brand and campaign. Unregistered traffic gets filtered by carriers. Ask:

• Do you expose registration through an API, or is it a console form?
• Can my customers fill in their own brand details inside my product?
• When a campaign is rejected, do I get a reason I can act on, or a generic code?
• What does registration cost per brand and per campaign, and is there a setup fee?

On Ready, registration runs in-app and through the API (GET /v1/registration returns status). A brand is $25/mo for registration, plus $2/month per number. There's no setup fee: the charge at submit is the first month, $25. Most approvals take 2 to 7 days. Rejections are common, and the usual cause is sample messages, which we cover in our SHAFT rejection rewrite guide. Details are in the docs.

2. What throughput will I actually get on day one?

Throughput is set by carriers based on your campaign's use case and brand trust score, not by the vendor. Carriers publish no official rate card, so treat every figure here as a rough approximation. A fresh standard campaign with no vetting often lands around 1 to 4 segments per second. Higher use-case tiers can reach roughly 10 to 75. T-Mobile also applies a daily brand cap by trust score, roughly ~2,000, ~10,000, ~40,000, ~100,000 or ~200,000 messages a day, lowest score first.

Here's a worked example. Assume 15,000 segments at an assumed 3 segments per second. That takes 5,000 seconds, about 83 minutes. If you promised customers an "instant" campaign send, you need to know this before launch.

Ask the vendor whether they queue and pace sends to your limits or simply fail when you exceed them. Also ask whether they can help you raise the trust score. Optional brand vetting ($79 Standard / $179 Enhanced, one-time) can lift the daily cap if it moves you across a tier. It doesn't change the per-second rate. Whether that's worth paying is its own question, covered in Is 10DLC brand vetting worth $79?.

Cost: the two questions that change your spreadsheet

3. Are carrier fee fees included in the quoted rate or added on top?

Carriers charge a per-segment fee on A2P traffic. Some vendors fold it into a single per-message price. Others list it separately. Neither approach is wrong, but you can't compare quotes until you know which one each vendor uses. Ask for the carrier fee as its own line, per carrier, in writing.

Ready's Standard rate is $0.0075/segment plus a $0.0045 carrier fee itemized on the bill. That all-in figure excludes the optional compliance surcharge described under question 6. The breakdown is in the pass-through line item explainer.

4. How are segments counted, and are inbound messages billed?

Vendors bill per segment, not per message, so this matters. A single segment holds 160 GSM-7 characters. Longer messages split into segments of 153 characters each. One emoji drops the limit to 70 characters, or 67 per segment in a multipart message.

Here's a worked example on Ready Standard: a 175-character promo sent to 5,000 opted-in contacts.

• Plain text: 2 segments per message × 5,000 = 10,000 segments. That's $75 in Ready fees plus 10,000 × $0.0045 in carrier fees.
• Same text with one emoji: 3 segments per message × 5,000 = 15,000 segments. That's $113 in Ready fees plus 15,000 × $0.0045.

One emoji added 50% to the bill. Ready swaps curly quotes, long dashes and ellipses for plain ones before sending, so pasted copy from a doc doesn't silently push you into unicode.

Also ask about inbound messages. On Ready, replies are billed like sent texts: the per-segment rate plus the carrier fee. Some vendors handle inbound differently. Pricing clarity means you can predict a month's bill from your send plan, so ask every vendor to price the same sample month.

Compliance plumbing

5. What happens when someone texts STOP?

Every vendor will say they "support opt-outs." What you need to know is what that means in practice. Ask:

• Is STOP honored automatically?
• Does the opt-out apply across every campaign and every number in the account?
• Can I read the opt-out list through the API?
• What happens if my code tries to send to an opted-out number anyway?

On Ready, inbound STOP and UNSUBSCRIBE are honored, and the opt-out propagates so the contact can't be messaged again across campaigns. You can query opt-outs with GET /v1/opt-outs and GET /v1/opt-outs/:phone. Sends to opted-out numbers, numbers on your Ban list and known landlines are refused up front and not charged. Campaign and automation texts that would land in the recipient's quiet hours are held and sent later, and charged only when they send. A single API text is held only when the window opens within about 6 hours; otherwise it gets 409 QUIET_HOURS_BLOCK, nothing is sent or charged, and you resend it later. Background on the rules is in our opt-out guide.

6. Is DNC and litigator scrubbing built in, or a third-party integration I maintain?

TCPA exposure runs roughly $500 to $1,500 per text. Many raw APIs leave scrubbing to you, and with enough engineering time that's a workable setup. Ask whether scrubbing is available, how it's priced, and whether it can run automatically on every send.

On Ready, scrubbing and landline validation can each be switched on per account at $0.003 extra per segment. Both are off by default. There's also a standalone scrub at $0.005 per contact (GET /v1/scrub/:phone) and number validation (GET /v1/validate/:phone). The scrub checks known TCPA-litigator lists and DNC-complainer lists. It reduces risk. It does not make you lawsuit-proof, and consent is still the sender's responsibility. Ready records the sender's opt-in attestation for each campaign you send and each API send that attests consent (who sent, to how many, when). It does not store per-contact consent, so the recipient's opt-in time, wording and page URL stay in your own records. (A contact who signs up on a Ready-hosted opt-in page is the exception: Ready stores that sign-up, with the time, IP address and exact wording, and support@tryready.com can send you a copy.)

Multi-tenant and channels

7. How do sub-accounts work, and what's isolated?

For platforms, this is the question that decides the build. Ask whether each of your customers can have its own:

• numbers
• 10DLC registration
• opt-out list
• billing

Also ask whether sub-accounts can be created by API, and whether one tenant's bad sending can affect another's deliverability.

On Ready, each customer gets a sub-account with its own numbers and carrier registration, created with POST /v1/sub-accounts. If your product is GoHighLevel-based, there's also a native OAuth integration that maps sub-accounts per location with two-way sync.

8. Can I send iMessage, and what are the limits?

More buyers are asking about the blue bubble, and answers vary widely, so ask directly. Ready's blue line sends as iMessage with the business's name and photo. It needs no 10DLC registration, so a business can start texting as soon as the line is set up.

Pricing and limits:

• Cost: $99/month per line plus 6 cents a segment. Replies are also 6 cents a segment, and reactions are free.
• New conversations: each line can start up to 50 new conversations a day.
• Before a reply: up to 2 texts to someone until they reply, and photos only after they reply.
• Android recipients: texts go from the account's regular number. If the account already had a number they bill at the regular text price; if the blue line came with its green number, they bill at 6 cents a segment once the account registers.
• Campaigns: campaigns and drip campaigns send from regular numbers, not the blue line.

The blue line is not Apple Messages for Business. A blue line can text first. See the blue line guide and API docs.

Building and running it

9. Is there a test mode, and how close is it to production?

Ask whether test credentials simulate sends, whether they fire webhooks, and whether anything billable can slip through. Also ask what it takes to send a real message to your own phone.

Our honest answer on Ready: a test key (it starts rsms_test_) simulates sends, number purchases and registration, so nothing is sent or charged. Other writes are refused and reads are real. For real sends, the first 20 one-to-one texts are free, and to send any text you need a card and a number ($2 a month, the first month charged when you get it). Use them before you register, because the free texts end once a registration is paid for. Send with an Idempotency-Key header so a retried request never sends twice. The integration walk-through covers retries and errors.

10. Who answers when messages stop delivering?

Filtering problems are rarely the API's fault. They're usually content, links or registration mismatches. Ask the vendor:

• Who looks at a filtering problem: a ticket queue, or someone who reads carrier responses?
• Is there a status page?
• Do you help diagnose content-level blocking, or only confirm that the API returned 200?

Get the support tier and its response expectations in the contract, not the sales deck.

When a pure API provider is the better fit

Be honest with yourself here. Raw CPaaS APIs like Twilio, Telnyx, Plivo and Bandwidth are priced at or below Ready's per-segment rate. A pure API is usually the right call if:

• you text only for your own business, under one brand
• you need global coverage, voice, video or email from the same vendor
• you have engineers who want to own registration, scrubbing and opt-out logic
• your volume is high enough that a fraction of a cent per segment is real money

Ready makes more sense when you're a platform and the per-tenant registration, sub-accounts, scrubbing and quiet-hours work would otherwise land on your roadmap. We compare on what's included, not on per-segment price, in our Twilio comparison.

FAQ

What is the best CPaaS SMS provider for a SaaS platform? The best provider is the one whose sub-account and registration model matches how your customers send. If each customer needs its own numbers and 10DLC registration, prioritize sub-account APIs and built-in compliance over the lowest per-segment price.

Is Twilio cheaper than other SMS providers? Twilio's per-segment price is lower than many platforms, including Ready's Standard rate. The total cost also depends on carrier fees, registration fees and any compliance tooling you build or buy separately.

Do I need 10DLC registration to send SMS through an API? Yes, if you send business texts from 10-digit US numbers. Unregistered traffic gets filtered by carriers, and most approvals take 2 to 7 days.

How do I compare SMS pricing between providers? Price the same sample month with every vendor: segments sent, replies received, carrier fees and registration. Ask whether carrier fee fees are inside or outside the quoted rate.

Can a CPaaS provider send iMessage? Some can, but the terms differ, so ask about price, daily limits and Android fallback. Ready's blue line is $99/month per line plus 6 cents a segment, with up to 50 new conversations per line per day.

Where to go from here

Send these ten questions to every vendor on your shortlist and score the written answers. Don't score the demo. If you're a platform texting on behalf of your customers and want to see how Ready answers them in practice, the quickstart gets you to a first API send, and you can create an account and use your 20 free one-to-one texts before you register.