How It Works
An IXC carries traffic, usually voice traffic, between telephone exchanges. Telephone exchanges are usually identified in the United States by the three-digit area code (NPA) and the first three digits of the phone number (NPA-NXX). Different exchanges are generally in different geographic locations, such as separate central offices (COs, also called "wire centers").
IXCs originally carried voice traffic on analog lines, but voice traffic has since become largely digitized. Therefore, voice traffic is more typically a data stream and can be intermixed with data traffic such as uplinks for DSL. Most commonly, links between an IXCs and COs are ATM links carried on optical fiber.
For voice traffic transfer, IXCs use Softswitches that implement Session Initiation Protocol (SIP), which corrects errors. ITSP’s can thereby offer calls between Internet Protocol Phone to regular phone, computer to computer, computer to phone, and IP devices to other phone services.
Read more about this topic: Interexchange Carrier
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