Cheapest way to send SMS for number verification?
ApiMobileSmsMessageSms GatewayApi Problem Overview
My application needs to verify phone numbers that are provided by the user. What is the absolute cheapest way to send an SMS to a phone? Which company/API should I go to? I'm not looking for a hack solution to send out 10 SMS a month kind of thing, I need to roll this out for a company that will be sending mass amount of verifications. But they want to do it at the lowest cost. (Each user will only need to verify once)
Sorry forgot mention the SMS needs to be international
Api Solutions
Solution 1 - Api
I'd suggest using TextAnywhere:
They provide API's (C, Java, .Net, PHP etc) for several languages and provide a multitude of rates and packages depending on the volume of texts sent.
They're also very flexible with regards to payment - they do pre-pay, PAYG and fixed monthly limits.
We used them for a large-sized application to send alert notification messages and they were very reliable. They also give 15% discount for registered charities and academic institutions.
Solution 2 - Api
Twilio is the best, fastest, cheapest and has a TON of amazing features you may choose to use in the future
Solution 3 - Api
You're looking for a bulk SMS provider that can send internationally. A web search for "bulk sms" will show tons, including some I have experience with: clickatel, mblox, clx. The simplest way to interact with such services is via HTTP by POSTing your submissions to their gateway.
Solution 4 - Api
The absolute cheapest way (I can think of) is set up a system yourself.
By a contract to some cell phone provider and hook this up to your linux computer.
http://www.dealextreme.com/details.dx/sku.12057
Here is a thread discussing the set up process on linux. It's not a walk in the park but it is cheap.
Solution 5 - Api
You might take a look at using a Google Voice API, because it'd be free. I'm not sure which language you're using but here's a API for python that should let you do it. http://code.google.com/p/pygooglevoice/
Solution 6 - Api
Try www.bulksms.com - they have been around for over 10 years now, and specialise in pure SMS messaging - nothing else. A simple HTTP API, good delivery, operational in UK, Europe, USA, Africa and more.
Solution 7 - Api
It's fairly easy to send SMS via email as well. The downside is that you need to ask the end user what country and carrier they have.
Solution 8 - Api
If you need verify an mobile number, not send sms and not confirm propietary, then you should search for "HLR Look up gateways", it´s cheaper than send SMS.
Solution 9 - Api
You could prefer to use Zeep Mobile API. It is free for development and bulk message. Only due to sponsorships, it inserts ads into your messages.
Still it is a good one and worth a try.
Best of Luck!
Solution 10 - Api
UPDATE:
Well a new service called Number Guru launch and they offer a developers API, not sure if it's free
OLD:
I would suggest OpenMarket as a SMS aggregator. They offer Number Lookups as part of their service if you needed two-way communication with a Short Code.
If you just need to send a one-way SMS/Text message (Like alerts) but the user would have to opt-out via email and then be removed from your service. You could use something like Neustar number verification LEAP to do a number lookup (Which displays the carrier information) and use the SMS Email Gateway to send the SMS messages.