I have few points to I want to make. I am basing my opinion based on my development experience on similar solutions,
mypaga.com, and also because of the attempts we are still making to provide it in Ethiopia.
1 - Security - you can not relay on any service provider to do the security for you. It is all about your design and communication. There are standards you solution needs to meet in order to be acceptable internationally. And most of these standard checks look at your solution internally than externally. The only issue I see with Ethio Telecom is the ability to host dedicated servers with no downtime.
2 - M-pesa - If you look at the business model that M-pesa has, it would not fit Ethiopia. M-pesa is big in Kenya for a reason. I don't see it replicated anywhere else in the world. The solution we should think of should be open to integration with many different types of organizations.
3 - Integration - If you want to implement such a solution, you will need to integrate with different entities. Most of our banks, service providers, and important institutions will need to build their solution and expose it initially. eg. if you want to be able to top-up airtime, you will need to integrate with Ethio-Telecom services. I don't know if such a thing exists at the moment.
4 - Technically/Financially sound - If you see how other payment platforms are designed, eg paypal, you will immediately realize the amount of energy and time it takes to build it. There is a lot of investment going into building a world class solution. So there needs to be capital ready to do this. i.e. Financially capable of running the business for months without profit, marketing to penetrate through Ethiopian mindset, Engineering setup and running costs and much more. So I am not sure if there are Angle investors but you will definitely need them.
5 - Banks - Banks play a great role when it comes to financial solutions. Not only are they policy makers but are also active players in this. I see a lack of technical capability in most banks. This is not to say the don't know what they are doing but rather to say that they don't have the capacity, at least at the moment, to cater such needs.