Lets look at the Paging Device

Paging Technology (from Wiki)
There are several protocols for Pager Technology, I will try to find out more about the ones adopted in Asia.
A brief description about one of the Alphanumeric Paging protocol....
Telocator Alphanumeric input Protocol [http://www.tap-ixo.info/how-tap-works.htm]was also known at PET and IXO protocol. This protocol was used for sending one way alphanumeric pages. Originally, devices like the IXO Device were used to send Alphanumeric Pages using TAP. Later, Motorola would create a similar device called the AlphaMate. TAP Protocol is still used today in the still existing one way paging customer base and also to send one way messages to cellphones. In 1996, RAM Mobile Data introduced extensions to TAP for two way paging over the Mobitex network.

The Future
"Recent developments in pager technology include the ability to transmit a limited number of pre-programmed responses back from the pager to the caller via radio signals. For example, this would allow the pager user to send a message of "buy" or "sell" in response to an urgent inquiry from his or her stockbroker. Two-way communication via pager is expected to expand in the near future"

Excerpt from - - http://www.madehow.com/Volume-2/Beeper.html