I'm working on a startup idea (have been for a few months, in fact). Part of this idea revolves around sending SMS reminders/alerts to my customers (fairly heavy usage).
The startup is to be based in the UK and target primarily the UK market which has very patchy support for the email-to-SMS gateways you guys in the US seem to have - not that that would be an ideal solution since you need to know their provider.
I was planning on integrating with Twilio 's SMS API, which looks great (and I still might, depending on the answers here!) but at £0.03 per SMS, it could end up eating into my profit margin too much, given the price point for my product/service I've deemed necessary to shoot for.
What are my other options? Can I buy a mobile phone on a contract with unlimited texts and go-about integrating that with my app somehow. Or can I buy some kind of GSM modem or something? I don't know much(/anything!) about this.
I thought here would be the most appropriate place since it's something many start ups have probably had to tackle and is more a question of "how do I do this cheaply for my startup?" than asking for advice on the specific technical implementation.
3p is about average for sending SMS messages in the UK, you'd be hard pressed to find something cheaper. I would consider, rather than Twilio, using BulkSMS. I have used these in the past and can vouch for their reliability on the basic package (this is only a personal recommendation though, I haven't used Twilio!).
To cover your final statement with regards to a contract phone, you can of course do this, but it's normally against the terms of service for this kind of usage. What you could do, though, is call up a business manager at one of the phone networks and discuss your options, they may be able to at least match a deal or even beat it if you were on one of their not "unlimited" packages - just explain your situation clearly.
For business tariffs, T-Mobile seem to be the best in the UK, so I would speak to them first.