The Comstar company develops and sells business telephone and data systems. They provide businesses with many different services involving data and telephone.

David Talley has written:

'Basic telephone switching systems' -- subject(s): Automatic Telephone, Telephone systems

'Basic electronic switching for telephone systems' -- subject(s): Electronic Telephone switching systems

Vonage Telephone Service and Charter Telephone Service are some of the best telephone systems you can find.

Here are some telephone system that are available: Calling Systems, Best Choice Business VOIP, PBX phone systems, Business phones systems, Nationwide Telephone numbers,

No, telephone area codes are discrete data.