We can offer a wide variety of services with 900.
Below are a number of different solutions which include pay per call billing:
Using 900 in mobile apps
Apple and Google are very restrictive in allowing third party in app payment solutions for apps in their Google Play or App Store. We recommend using 900 in a mobile web interface i.e. a mobile app. Alternatively, the customer receives a link with a click-to-call number which can be read from the mobile phone.