Hello,I am currently doing a similar project with this kind of SMS servicing in Malaysia,hope the following info will help you to have a general idea of current SMS service.
Actually, there are a lot of sms service providers here which you could choose any of those, general speaking most of them could provide you a website which u can login into and create account, or group of accounts and send group sms to these users, u can even upload your database which may contain your customer's handphone numbers,as you can see this is a very easy way to do the group sms sending.
Another way is to get an API from SMS service providers, then you start to coding and make your system able to communicate to their sms server through API, anyway i think the type of programming language you chosen is irrelevant to the type of language your sms service providers chosen to develop the sms system.
Sincerely,
Daniel
PB: Sorry for that i couldn't type chinese on my notebook here.