We use it and for us it is an excellent asset for getting payment, we average about 15% of payments through this system, which if balance your cost as follows:
Collecting - Time, Manpower, Vehicle wear & tear, Fuel,
Cheques - Waiting for payment, banking fees, time doing banking
S/Order - We use it, its excellent and easy to manage
C/Card - Lowers running cost than collecting or Cheques, instant payment.
Most mobiles offer a package for free landline calls, use this package and call your customers.
Just my opinion for what its worth?