Merging Wireless Networks and the PSTN
This Section explains the merging wireless network and PSTN
How to merge:
As first generation wireless systems were being introduced, revolutionary advances were being made in the design of the PSTN by landline telephone companies
The overhead required in the PSTN to handle signaling data on the same trunks as voice traffic was inefficient, since this required a voice trunk to be dedicated during periods of time when no voice traffic was actually being carried
The advantage of a separate but parallel signaling channel allows the voice trunks to be used strictly for revenue-generating voice traffic, and supports many more users on each trunked line
In mid 1980s, the PSTN was transformed into two parallel networks — one dedicated to user traffic, and one dedicated to call signaling traffic. This technique is called common channel signaling.
In many of today's cellular telephone systems, voice traffic is carried on the PSTN while signaling information for each call is carried on a separate signaling channel
In first generation cellular systems, common signaling channels were not used, and signaling data was sent on the same trunked channel as the voice user
In second generation wireless systems, however, the air interfaces have been designed to provide parallel user and signaling channels for each mobile, so that each mobile receives the same features and services as fixed wire line telephones in the PSTN.