@joe: You need to know perl and use the Device::Modem package to send AT commands. Well, that's not the only way but it's the way I'd go. Then you need a gsm modem that can talk to your (linux) box bila shida. I have had my eyes on the Siemens TC35i terminal (asked about it on the list sometime back) and eventually found it here<http://www.warburtech.com/gsm/tc35i.terminal/>. Nobody has it locally to my knowledge - even the local Siemens guys had no info on it when I called them. In the meantime I have fooled around with minicom on phones, (Nokia 1680, 1200, N95 and N97) on connecting to the STK but I could not get any concrete info on Nokia STK commands for them. However I believe there are some older siemens phones (circa 2005) which can do the job...though I have not tried them. It supports the STK AT command set well, the Siemens documentation is online (even on the link above), just google kidogo and you'll get it all. IMO many modems support AT commands but their coverage on STK in particular is sketchy. The other GSM modem I know of is the Wavecom brand, might be hard to get hold of locally - I hear their chipset is used in Psitek modems (south african) - but I'm not sure. There's an asian site I stumbled upon a while back that claims to have safaricom as one of their clients who purchased the programming API from them (for .NET platform if I'm not wrong). Shida is I've been busy on an in-house coding project (that's me procrastinating, lol), but I guess I'll just paypal them tomorrow and tinker for myself when it arrives. As I have read you can control the STK menu via AT commands with the Siemens and Wavecom modems, provide inputs to prompts and get replies. I believe this is what you're looking for. Once you can talk to it with perl the rest is simple to figure out - making db connections and a web frontend. Methinks with this you can automate payments for all gsm operators on a small scale without having to break into their code on the sim and have an army of lawyers after your backside. My silent prayer is that safcom increases their mpesa transaction limits, esp with Orange Money's recent entry and terms. @zack: People have prayed, cried, ranted and raved about safaricom releasing an API but I do not see it happening anytime soon. Not when they consider data and financial transactions to be their most-sought-after revenue stream over voice.