Software to manage SIM Card Modem for Airtime Recharging through USSD Calls (RPA and AT Commands)

I need a custom Software to manage a Multi SIM Card Modem to recharge airtime to our customers. The main features are: 1.Receive and read SMS from the customers; 2.Charge the customers though M-Pesa payment API; 3.Run USSD Calls and follow the Menu to recharge airtime to the customers; 4.Robotic Process Automation to manage the sales; 5.Modem programming with AT Commands.

if you have any more questions you can ask

and after you completely understand all the requirements of the project you can tell me:

1.Estimate cost to complete the project?

3.Deadline? 

4.Scope of work? 

Just so i can have an idea and discuss with my brother