Access facebook over USSD
There are many value-added services (VAS) that can be offered using USSD. Facebook over USSD is one of them. Why we need this over USSD? The answer lies in the main feature of USSD. USSD sends entered strings or text from mobile devices to the home network or a USSD gateway and vice versa. It does not require an internet connection or a smartphone. This is mainly used in countries where people have a lesser number of smartphones and a mobile operator wants to open new channels for the revenue.
The main issue with USSD is that it limits the number of characters over the GSM network. So for long text, VAS provider does many message transaction to get the string.
VAS application for facebook:
The first thing for providing service, a VAS provider deploys a USSD application over a server. The server connects to the mobile network over the SS7 protocol to interact with the mobile user and connects to the internet for facebook access. A shortcode is assigned to the application. So that if a subscriber dials short code, USSD call reaches to the server and a session is started.
The call flow for facebook over USSD:
A mobile user dials the string (e.g *456#) for accessing facebook.
String reaches to the application.
Application cheeks for the subscription. If a mobile user subscribed for service, the USSD application displays the menu to the handset, which asks for facebook user name and password.
After getting a user name and password, an application calls the authentication API of facebook to get the token.
Once a token is generated, the application displays the facebook options (e.g post on a wall, like, etc.) to the subscriber.
The subscriber chooses the option and the application calls the corresponding facebook API for the action and returns the result to the handset.
On logout service provider deletes the access token for facebook.