VoIP works with a company’s existing telephony architecture, including its private branch exchanges (PBXs) and analog phones.
VoIP and H.323 enables companies to complete office-to-office telephone and fax calls across data networks, significantly reducing tolls. New applications are available, including unified messaging that integrates e-mail with voice mail and fax.
Customers may choose VoIP as their voice transport medium when they need a solution that is simple to implement, offers voice and fax capabilities, and handles phone-to-computer voice communications. IP networks are proliferating throughout the marketplace. Thus, many customers can use VoIP today.
Integrating Voice and Data on the WAN
The Voice over IP and H.323 standards define how analog voice is converted to data packets and back again. The next step is to use a company’s existing wide-area network (WAN) to transport voice traffic with data traffic.
Serial (Leased Line) Services
T1 is a private-line digital service, operating at 1.544 Mbps in a full-duplex, TDM mode. The 1.544-Mbps transmission rate provides the equivalent capacity of 24 channels running at 64 Kbps each.
The full-duplex feature of T1 allows the simultaneous operation of independent transmit and receive paths. Each data path operates at a transmission rate of 1.544 Mbps. Companies that need less bandwidth can deploy fractional T1 trunks, using any number of channels needed. A fractional service is tariffed on a linear pricing schedule, depending on the number of T1 channels and the distance covered.
The TDM feature allows logical channels to be defined within the T1 serial bit stream. The T1 bit stream may be channelized in many different ways, as follows:
- – A single 1.544-Mbps digital channel (non-channelized) between the user’s premises and the central office (CO)
- – 24 independent channels, each providing 64 Kbps of bandwidth
- – Any variation of 64-Kbps channel combinations
Each logical channel may be independently transmitted and switched. A combination of voice, video, and data may be transmitted over a single T1 line.
Ideal Applications for T1 Services T1 service is ideal for applications that require continuous high-speed transmission capabilities.
Some common T1 applications include the following:
- – High-volume LAN interconnection
- – Integrated voice, data, video, and imaging transmission
- – Compressed video transmission
- – Bulk data transfer