AT ITEXPO Paul Bassa, VP Product Marketing gave me an overview of U.K.-based DIGITALK, which offers platform and application products backed by full services support, that offers provisioning, prepaid charging, payments, and carrier routing to minimize operations overheads and maximize service margins. They offer pre-sales consultancy, through installation and commissioning, to worldwide 24x7 SLAs.
They offer a mobile VoIP app on consumer side and allow service providers to white label the app and they help with the Apple iTunes app submission process. The mobile VoIP app has prepaid capabilities built-in, allowing you to simply enter a PIN to activate.
They build all their own products, including their own session border controller (SBC) and can do carrier to carrier routing, management, SIP trunking, wholesale billing, and reporting. They also have a Web API to allow you to build your own portals. They really are a one-stop shop for service providers looking to do prepaid, peering, termination, SIP trunking, prepaid mobile video, IP virtual office, and solutions for MVNOs, MVNAs, MVNEs, and more.
Here's Paul's short video overview of DIGITALK: