Alphanumeric pagers offer a high level of information content and utility to subscribers, but their cost is high in comparison to the numeric display pager. The cost of telephone operators to answer calls and type in the text messages must be factored into the cost of subscription to this type of service. In the past numeric display paging could not be offered on an automatic basis like in the US and other countries, because of the technical limitations. The Technical Limitations D.I.D. trunks make it possible for the telephone network to forward the called number to the paging system. When someone wants to send a page, they just dial a telephone number and the paging system automatically knows who the call is for.
Every subscriber has a unique telephone number.
Without D.I.D. someone has to ask . That means live operators. With Touch Tone TM telephones, the calling party can dial in the number to be sent to the pager. Without Touch Tone TM , someone has to ask . Rotary or dial-pulse telephones will not work.