We used to have a service called sms2fon which we developed before but we do not have it right now. its a service like when we send sms to a specific number it sends that sms to our VoIP switch and it initiates a call back to the sms sender and whom he would like to call . It is based on a concept called smstools and it can be done on linux, or windows or solaris. I prefer in Linux. It also uses perl and php. It is the same concept like jajah or click2call but they do it thru wbe we need it thru sms but its the same concept. If you have ever dealt with voIP or such application you can bid. if you have no idea what i am talkinga bout please do not bother to bid and do notw aste my time by contacting . after you bid i will ask some question concerning the project then only the project will be awarded..