1.7. Key Issues: Voice and Data: Two Separate Worlds
The PSTN developed as a result of early telephony pioneers' efforts at building meshed and switched networks.
SS7 is the switch-to-switch signaling network using to connect and bill calls placed across the PSTN.
POTS, or plain old telephone service, is the basic single-line analog voice service from a phone company.
Key systems and PBXs provide businesses a way of operating their own feature-rich voice networks at a lower cost than dealing only with PSTN-provided services.
Lines and trunks are links between telephony devices. A line is a link from a switch to a phone. A trunk is a link from a switch to a switch.
Voice over IP encompasses a large family of interface technologies, protocols, and standards that enable real-time media applications using IP networks.
Traditional telephony isn't scalable like VoIP because it isn't software-driven like VoIP. Its ratio of calling capacity to network infrastructure is fixed, while VoIP's has lots of room for optimization.
VoIP is suitable for deployment in homes and businesses, and, thanks to broadband and deregulation , is earning a reputation as a more practical way of delivering telephony services.