Figure 2.1 A hybrid system with circuit switched PBX and Voice over IP capabilities.

VoIP, PBXs and Cabling In this chapter understand: –The structure of VoIP based telephone systems vs. traditional PBXs –Applications such as voice mail, ACDs, unified messaging and integrated voice response, and how they are connected to telephone systems –Characteristics of unshielded twisted pair and fiber optic cabling

TDM Vs. IP End Office tandem Reserved time slots Softswitch Voice digitized, compressed & put into packets Packets interleaved as required in no special order

Figure 2.2 Circuit switched PBXs connected to a data network for Voice over IP traffic.

Figure 2.3 Connection to a branch office Voice over IP telephone system.

Figure 2.4 Courtesy of Avaya, Voice over IP softphone with the same extension number as the desk telephone.

Figure 2.5 PBX trunks from the telephone company to the demarcation.

Figure 2.6 Direct inward dialing (DID) carried on a T-1 trunk to an IP-based telephone system.

Figure 2.7 In-building wireless service.

Figure 2.8 One-number wireless service in conjunction with a PBX.

Figure 2.9 Integrated voice response system linked to a computer and an ACD.

Figure 2.10 Queue management software linked to an server and PBX.

Media What are my choices? What are the criteria for selection? Implication of choices

Figure 2.11 Cross section of Category 6 cabling.

Fiber Applications & Characteristics Characteristics –Performance –Electrical immunity –Security –Durability –Cost –Size –Weight –Flexibility –Material & labor costs Applications –CATV –Backbones –Trans oceanic routes –Cellular backhaul

Figure 2.12 Fiber optics in cable TV networks.

Impact of Wavelength Division Multiplexing Dense Wavelength division multiplexing Amplifiers Dense vs. Coarse # of channels Costs

Figure 2.13 Coarse wavelength division multiplexing (CWDM) in cable TV networks.

Summary Traditional PBXs differ from softswitches in the following ways: Customers purchase VoIP based switches because: How do customers insure security? How do fiber cabling and unshielded twisted pair differ from each other? In what applications are fiber rather than copper used?