Just want to correct this list, as we definitely do support SSL, and we've just upgraded the certificate: https://www.clockworksms.com/blog/ssl-sha2/
If SSL isn't enough, we can also do VPNs directly to our (only UK based) datacentres.
Feel free to ask questions if you have them. We've got good links to the US and great coverage throughout the rest of the world
I wanted to add Mblox to this list, if possible. We provide HTTP, Rest and SMPP connections, along with web based applications. We have over 100 direct operator connections, as well as global coverage to over 978 networks.
We offer MMS support within the US as well as approved US & Carrier SMS connections. I will be more than happy to speak to anyone regarding their requirements - please get in touch, Sarah.Cruttenden@mblox.com
Look forward to hearing from you,
Developers use our Subscription API to trigger an interactive SMS or IVR call campaign (that they've built via our website first) - by simply sending us the campaign ID and the recipient's phone number. This saves them days/weeks of coding to Twilio/Plivo/etc's APIs and they offload all changes to the interaction flows to their business team members. We've been used in 80+ countries, including by Intel and UN WFP. :)
We have the most experience in the UK market because this is where we do most of our premium sms/direct billing business under another company (http://www.fonix.com/) but we support bulk messaging to a lot of different countries (https://zensend.io/pricing).
I had my outsourcer do it. not sure if they scraped it or used LinkKlipper.
So that tends to be a lot of stuff.
I would be really interested in SMS deliverability data by country or region for different SMS API providers. I think it is really key when choosing SMS providers, and it is hard data to get.
We changed our name long ago and along with the name many other things:
We support SMPP, SMPP over TLS, http apis that support TLS (with libs in many languages https://github.com/messagebird), SS7, easy delivery over all over the world (except North Korea).
And many more exciting stuff coming up.
Always negotiate lower prices and shop around.
Nexmo has great analytics that show failures. Plivo will just fail and not log it and not return a failure, so I'm migrating away from them.