Twilio vs google voice api for SMS

Question

I am building a mobile app (android et al) that I need to use SMS for. The SMS would simply send an activation code when user first registers with my app (and maybe one other equally simple usage). Since Google is a respected company and Google voice is free (API), I was thinking of going with Google Voice. However, a lot of developers seem to be using Twilio. Is there an advantage to using Twilio SMS over Google Voice SMS for my basic usage of sending verification code (again, Google Voice is free)?

Solution 1

Google Voice appears to limit the number of SMS messages that can be sent. They don't go into detail about the limits.

To prevent abuse, there are limits to the number of text messages you can send from Google Voice. If you've reached the limits, you will see a message that says 'Your message was not sent because the text message limit was reached. Please try again later or try sending to fewer contacts.' You'll have to send to fewer people, or try sending your text message at a later time.

Twillio does also limit the number of SMS messages, but it's a documented limit.

Each Twilio SMS-enabled long code (regular 10 digit number) can send 1 SMS message per-second, per-number. Unfortunately we are not able to adjust this rate limit. If your application requires a high volume of outgoing SMS, we recommend using an SMS short code.

So I guess the difference is, one may cut you off, but is free. The other won't, if you stay with in their limits, but costs money.

Solution 2

The API you are linking to is not an official Google API and therefore there is no guarantee that either it will work reliably or that Google will not decide to disable the API at some point. So you are paying for a level of reliability rather than relying on an unofficial hook into Google Voice.

There are lots of SMS APIs available, Twilio is a well known one for sure but there are others. Take a look at another answer I posted a while back listing some of the providers. How to send SMS programatically in a professional and reliable way?

Comments

[learner]

I upvoted. I am waiting to see what others have to say. My SMS will go out each time someone opens an account. So unless google is very stingy their limit should really not be a problem. But then the unspecified thing is a problem.

[learner]

good job on being so thorough. Is it an exhaustive list? :) Thanks.

[Rod Burns]

Not exhaustive sadly, there are so many now (probably mostly built on top of the same supplier) but it covers the most well known ones.

[Rod Burns]

Thought I would add this blog post link, seems Google is partnering with Twilio for sms rather than releasing their own api blog.programmableweb.com/2013/04/04/…

[toddmo]

It is a problem. Google can change the rules and you won't know, and thus the behavior is completely unpredictable and not a viable IT solution.

[DanT]

I've been told by a Twilio person, that you shouldn't send more than 250 messages a day per number, otherwise you might be blocked by the mobile providers. An exception are Twilio short codes.

[Cheeso]

@RodBurns regarding your comment... my understanding of the blog post you cited: Google has produced Java and Python libraries that allow apps on Google App Engine to call into Twillio. It says nothing about "Google is not releasing an API for Google Voice." It says nothing about Google Voice at all.