SMS and Voice API

How to Choose the Best SMS API in 2023

Louis-Victor Jadavji
Louis-Victor Jadavji
CEO at Taloflow
May 9, 2023
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Twilio -- what? Sendgrid -- who?

It can be an overwhelming choice with the multitude of SMS API services now available. Today, we’ll go in-depth into what an SMS API is, its benefits over email communication, and the key questions you’ll want to consider before choosing an SMS platform.

With all the noise of social media notifications and inboxes full of thousands of unread emails, SMS is not only a relevant marketing channel in 2022 but can be one of your product’s key differentiating factors.

SMS APIs are used by companies and startups of all sizes and use cases. Not only do they offer core integration via notifications for your app or business, but SMS APIs can alleviate the hassle of writing custom code and ensuring deliverability. These features allow for a hassle-free and effective marketing channel or notification system for your app. Since your SMS API provider will be tightly tied to your software’s design, making a split decision can lead to technical debt that will be expensive and time-consuming to backtrack.


If you’re short on time, here are the highlights:

  • An SMS API allows you to send text messages with a single HTTP request.
  • Some SMS API providers perform better in specific regions, while others have extended from the core SMS offering to other communication-related APIs, like a Whatsapp API.
  • SMS has a vastly superior open rate compared to email.
  • Some providers will still charge you even if the SMS message is not delivered.
  • Direct connections to the mobile network are the most reliable, but some providers will use less reliable “grey” routes to deliver your message.

What is an SMS API?

You probably already know that an API allows for programmatic communication between networked computers, but how does an SMS API work? Like many API providers for services like geolocation, data processing, and AI, SMS API providers allow you to send Short Message Service (SMS) or text messages to consumers, usually with a single HTTP request.

SMS APIs take care of all the heavy lifting of sending SMS or text messages to users. SMS API providers partner with network carriers and providers to have a direct and reliable method for sending SMS messages.

What are the top SMS API service providers?

Twilio has been dominant in this space, has extended well beyond the scope of SMS API, and is easily considered one of the pioneers of the full-fledged cloud communications platform or CPaaS (Communications Platform as a Service). However, multiple competitors have expanded significantly within niches like omnichannel customer support, video communication APIs, and push notifications. Some even focus on building best-in-class tooling for specific social networks, like Whatsapp or Instagram. There are also noticeable differences in these services' reliability and deliverability rates based on your target regions. Some upstarts have honed in on this, like Gupshup in Latin America.

The most prevalent SMS API providers include (in no specific order):


Telnyx SMS platform landing page

As you may have noticed at this point, most major vendors offer largely comparable features with minor variation in their specialization and pricing. Telnyx is no exception: its API supports all of the same features mentioned thus far – MMS support, message queueing, global coverage, et cetera – but places an emphasis on lower pricing, with its website openly advertising an average 70% of savings compared to some of the competitors we’ve listed thus far.

Specifically, Telnyx charges $0.0025 per SMS sent from local numbers, and up to $0.0070 per SMS sent for short codes, with number rentals running $1 per month for both local and toll-free numbers, or $1,000 per month for high-volume short codes pushing 100 SMS per second (higher volumes are available on request).


Twilio SMS platform landing page

One of the platforms that sees the most use with over 100 billion messages a year is Twilio – with a comprehensive feature set that includes shortcodes, international numbers, smart content handling, MMS support, delivery receipts, and more advanced messaging protocols like message queues, its SMS API has been proven reliable at scale at a level few others have.

Twilio’s popularity and success means that detailed documentation for just about any programming language can be found fairly easily, there are established support communities and libraries, and any issues you may run into have likely been discussed and resolved somewhere on Stack or Github.

Far as pricing is concerned, Twilio clocks in towards the upper end of most of these vendors, charging $0.0079 per SMS sent and $0.0075 per SMS received regardless of number or code type, with MMS costing as much as $0.0200 per message sent and $0.0100 per message received. It also charges $1 per month per local number rented, $2 per month per toll-free number rented, and $1,000 per month per random short code or $1,500 per month for vanity short codes rented, with an additional $0.0079 per message on any of these numbers.

That’s not only pricey, it’s the most expensive service on this list – unless you apply volume discounts, which can push per-SMS prices from $0.0050 after your first 5 million messages to as low as $0.0005 per message should your operation push past the 1 billion message mark. Unlike most other vendors, Twilio applies these discounts automatically and does not appear open to negotiation.

Needless to say, Twilio’s SMS API is geared towards bigger, more established operations that have both the resources to afford its pricing and the volume to benefit from its deep volume discounts.


Plivo SMS platform landing page

Plivo is another popular API with global coverage and a diverse number of shortcode applications ranging from SMS surveys and appointment reminders to two factor authentication and marketing campaigns.

Like Twilio, it benefits from established developer communities and resources thanks to its popularity, but it’s also significantly cheaper: depending on the source number type, Plivo charges between $0.0045 and $0.0055 per SMS, or $0.50 per month per long code number, $1 per month per toll-free number, and $500 per month per short code with an additional $1,500 one-time fee at time of purchase.

Plivo also offers volume discounts, but it does not apply them automatically, and they are subject to negotiation, meaning that you will need to reach out to their sales team should you anticipate volume in the millions.


Vonage SMS platform landing page

Vonage is a US-based cloud communications provider that offers a comprehensive portfolio of API services, including SMS functionality. Its SMS API places privacy and security front and center with primary applications in appointment scheduling and delivery confirmation, but also offers business analytics capabilities through its elaborate data management and reports API.

Vonage enjoys an edge in coverage and delivery optimization due to its global compliance engine (which circumvents the complexity of global carriers) and adaptive routing technology.

This service is the priciest yet, running around $0.0065 per message sent or $0.95 per month per number rented with prices varying depending on the kind of number and carrier. Vonage’s prices also fluctuate.

Bandwidth SMS platform landing page

Bandwidth is an established SMS API vendor that has earned high-value contracts with some of the biggest names in the game, such as Google and Microsoft. It operates its own nationwide network, 24/7 support, comprehensive analytics, and most prominently – flexibility. From group messaging to long form messages, from bot interactions to pin codes, bandwidth’s API supports any and all potential applications.

While Telnyx is able to charge less by cutting down on its margins, Bandwidth does so by operating its own network, which means that it is able to shave off middleman price padding that other vendors are forced to factor into their charges. All inbound messages are free, and Bandwidth charges a flat $0.005 per message sent or $0.35 per month per number. These low prices might differ for international applications, however, as Bandwidth’s network is based in North America and charges vary outside of the US and Canada.


MessageBird SMS platform landing page

Like Bandwidth, MessageBird has earned contracts with prominent companies like Facebook, Uber, Deliveroo, and WhatsApp, making it one of the safest picks with regards to salability, reliability, and coverage. It also features a code-free alternative to interacting with its API both through its drag-and-drop builders and point-and-click dashboard. However, as is true in most matters, convenience comes at the expense of flexibility and control – thus, MessageBird makes it a point to also give customers direct API access like the other vendors listed here.

Interestingly, you can take advantage of MessageBird’s global coverage and comprehensive documentation for free – the company offers a free “Startup” plan that includes unlimited team members, free WhatsApp approval, unlimited live chat conversations, access to all communication channels, 9 to 5 coaching support, a basic flow builder, an omnichannel widget, and an inbox. If you want actual API access, however, there’s no way around a price tag – MessageBird charges $0.006 per message in the US or $1 per month per number, with prices varying outside of the US.

Podium (campaigns only)

Podium campaign platform landing page

Where greater contrasts between feature sets and pricing models can be found are specialty-oriented services. Podium is a good example of this – unlike the other vendors listed here, it specializes in marketing applications and adjusts its messaging and key features accordingly by placing its 98% open rate text campaigns front and center on its homepage. It boasts ease of campaign creation and the ability to target numbers belonging to specific demographics, both of which serve to facilitate and support rapid marketing campaigns aimed at very specific target groups.

Its pricing model has also been shaped by this specialization. Podium offers three different packages: “Essentials”, at $289 a month, is intended for small businesses and comes with up to 1,000 contacts, supports up to 3 team members, and comes with online reviews and secure payment processing. “Standard”, at $449 a month, is intended for established businesses seeking to expand their operations. It includes unlimited contacts and team members, comes with personalized set up and onboarding, website reporting, custom branding, and hundreds of app integrations. Finally, the “Professional” package clocks in at $649 a month, also includes unlimited contacts and team member, and comes with all of the benefits of the other two packages as well as round-robin lead routing, automation functionalities, FAQ support, advanced payment options, and MMS support.

Gupshup (Latin America)

Gupshup SMS platform landing page

Specialty-oriented APIs can also take the form of services with more specific coverage that may offer savings when compared to the international fees vendors with global coverage may charge. Gupshup, for example, is a conversational messaging platform that specifically services Latin America (Brazil, Mexico, Colombia, and Peru, specifically) and India, with prices ranging from $0.020 per SMS to $0.0025 per SMS depending on the country.

Unfortunately, as one might figure, more niche applications usually translate into smaller operations, and that can mean less reliable service. At the time of writing, for example, Gupshup is experiencing technical issues that render its self-serve SMS messaging service inoperable, and another specialty service that was originally going to be included is now ramping down operations – permanently. Customers are, of course, notified of such complications and developments well ahead of time whenever possible, but this is nonetheless a factor in the decision-making calculus as you try to pick the right SMS API vendor for your business or operation.

SMS vs Email Performance in 2021

You might wonder whether Email APIs are enough. It’s already cheap and ubiquitous. So why would you ever consider choosing text messages as a notification channel? Although sending SMS is typically much more costly than email, the benefits are quickly noticeable. Check out the comparison image below, showing open rates, response rates, response times, and the number of users.

SMS boasts a 98% open rate above email’s paltry 20%, which is very tempting. So let’s say we’re convinced about SMS as a notification channel -- what now? Scroll on, and we’ll begin to ask the big questions about SMS API providers.

It’s also worth noting that many SMS API services are part of a broader communications platform portfolio that could include, among other things, an Email API service. Twilio, for example, acquired SendGrid a few years ago for the benefits you get when bringing SMS and Email APIs under one umbrella.

Comparison of SMS and Email results
Source: Adobe

Questions to ask before Choosing an SMS API

Due to the breadth of SMS APIs services available today, most come with standard features like MMS and rich media, two-way communication, bulk SMS messages, shortcodes and long codes, toll-free numbers, usage alerts, and much more. But if you want to go above and beyond with SMS, here’s what to look for when researching potential providers.

Does the SMS API offer a free trial account?

Ah, the free trial. A classic marketing technique and, to be honest, not a bad option for trying out a product. If you’re a friend of free trials, you’re in luck! Most SMS API providers offer a free trial. If they don’t, it’s worth emailing and asking. Ensure that the SMS API provider provides all of the features you’ll be using within your business during your trial. 

Many SMS API providers also offer a refund period if you are not satisfied with the service. Your vendor’s policies should be checked before making the final buy decision.

How is the pricing structured?

You have to pay the bills eventually. So how do SMS API providers bill you for the service you use? Some SMS API providers will bill on a credit-based system where you purchase a defined amount of sends upfront and refill as you go. While this is not always an issue, you should check that 1 credit is equal to a singular text message. Depending on the numbers you send the messages to, the number of credits you are using could be more than 1. 

Other SMS API providers may bill on an exact usage basis at the end of the month. Will you be sending a large number of SMS messages? There could be an opportunity to ask the SMS API provider about volume discounts. If you plan to send and receive SMS from users, you can expect to pay more but be more eligible for volume discounts.

SMS API pricing should be transparent and comparable with other providers regardless of the exact pricing structure.

Do you have to pay for undelivered messages?

Many SMS API providers charge for all messages delivered via their API, whether they get delivered or not. Be sure to see if your provider has a policy on undelivered messages and their average ratio of delivered messages. This doesn’t seem like a big deal, but this hidden fee could compound over time and run up a hefty bill you aren’t expecting.

Reliability, Deliverability, and SLAs

Although SMS is highly reliable, delivery rates will never be 100%. The deliverability ratio represents the ratio of total messages delivered to the number meant to be delivered. Many factors, including invalid phone numbers, telecom network issues, end-user problems, or even an issue in your API Provider’s network, can impact the deliverability ratio. At a minimum, your SMS API provider should have a method of letting you track delivery data in real-time, also known as delivery report notifications.

Another vital reliability metric is whether your SMS API provider uses direct network connections (also known as Tier 1 connections) rather than “grey routes.” Again, there can be a huge difference in reliability between the two. 

Direct connections are always the most reliable. It simply means that the messages are sent directly to the relevant mobile network (AT&T, T-Mobile, or Verizon, which are then passed to the relevant MVNO) versus being sent through non-direct grey routes. Those routes generally suffer from reliability issues and lack any form of delivery reports. If your provider is concealing whom they are sending from, that might indicate that they use grey routes.

Beyond using direct connections, your SMS API provider should have redundancy in place if their Tier-1 provider connection is unavailable. This link can be a “failover” to route messages in the case of an outage on the Tier 1 link. This is expected, but please exercise care with smaller and newer SMS API providers who don’t offer these capabilities.

Modern companies know downtime means lost revenue, whether it’s your mobile app, marketing website, or your SMS API provider. Most SMS API providers have a Service-Level Agreement or SLA in place, which refers to the amount of uptime they guarantee in a given period. For example, “5 nines” refers to availability as 99.999% uptime which equates to about 5.26 minutes of downtime annually. SLAs vary from provider to provider, with some even offering reimbursement on service costs if they don’t provide the amount of uptime they guarantee. 

Does your SMS API provider meet compliance standards? Do they deliver everywhere?

Sending notifications or messages by SMS is slightly different from email regulations. Your SMS API provider should comply with regulatory and legislative requirements depending on where texts are sent. For example, the US follows the Telephone Consumer Protection Act, specifically outlining how businesses communicate with customers over text.

You should easily be able to verify with your SMS API provider if they can deliver to the geographies your users reside in and that they do so in a lawful way. Many providers will describe regulatory SMS guidelines they follow for each country on their website. Most SMS API providers should have this documentation in place, but it’s something to be aware of for smaller and newer SMS API providers.

What are other users saying?

Getting a finger on the pulse of your SMS API provider from current or previous customers can save you a ton of time. If you're reading the testimonials on the API provider's landing page, take them with a grain of salt...those can be just a little biased. Finding unbiased reviews from real users can help you make a purchasing decision you won't regret. Consider the reviewer's viewpoint; if you see one or two bad reviews, that might be an edge case. However, if you observe many recent, consistently bad reviews, you might want to think twice.

Are the docs up to date?

Good API documentation is a developer’s best friend. Webhooks, tokens, and REST APIs should all be laid out clearly so you can develop without hassle. So check out your SMS API provider’s developer documentation. Is it in-depth? Does it cover-edge cases? Are there portions missing or paragraphs that leave you confused? 

Good documentation lowers the time and effort to integrate the API, but good documentation can indicate that the SMS API provider cares for their customers. If you are reading the docs and scratching your head, you might want to think twice and see if the docs reflect the company’s practices. 

API Integration Time

Tying into up-to-date documentation, how complicated is the solution to integrate into your use case? Many SMS API providers have a quick-start guide listed within their docs to get you started and send SMS messages within just a few minutes. However, if the SMS API provider takes a while to get integrated or is difficult to get started with, you might consider alternatives.

Development Libraries

All SMS API providers should, by definition, offer an API. This API should be callable from any programming language capable of making HTTP requests. These API calls, POST, GET, and others, allow your app or developers to interact with the API and send messages, update users, etc.

Many SMS API providers offer helper libraries for specific languages like Python, Ruby, Java, Golang, Node, and more. These libraries make interacting with the API and performing other common server-side programming tasks easier. You shouldn‘t consider this a killer feature, but give it some weight in your SMS API comparison.


It’s not hard to understand why SMS API providers pop up left and right. Using SMS as a communication channel can have some great benefits over email, including its’ open-rate. However, there are some key features and questions you’ll want to think about before exploring the best SMS API provider for your business.

When evaluating a potential SMS API provider, you should consider the pricing structure, deliverability, reliability, compliance, user reviews, and developer documentation. Hopefully, we’ve been able to provide insight into a few factors you didn’t think of for evaluating an SMS API provider.

No matter your use case, Taloflow can help your company find the best developer and cloud tools based on your exact requirements.


How to identify grey routes (

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High availability - Wikipedia

The Complete SMS API Resource - SMS Works

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