Hi we built a similar system before and based on the experience, in the Application we going to build for your needs will include the following basic modules and as for the base and manage the coding we will be using Codignitor Framework (that way we can structured the coding in MVC pattern) and following modules will be build as pluggable components. so that way you can extend the features later.
Customizable Dashboard
Customer Contact Mgt,
Customer Mgt,
Customer Supporting,
Order Management,
Billing & Online payment with payment gateway
Manage customers and Accounts (activation/deactivation)
Service Assurance (we can build this module if the data is provided by main system or some way)
Product Mgt (Service Catalogs),
Dealer Mgt,
Channel Mgt,
Reports
For the applicaton, may be we would need access to your main database which normally build with oracale or sql server to retreive data. I belive it already have some sort of API solution which we can query and receive the data.
And the featurs are above are general and we can discuss more about the customizable modules in project desciription
Thank you
Patzz