Cisco Cisco Serial Port Adapters Data Sheet

Data Sheet

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Cisco 4-Port E1 G.703 Serial Port Adapters

Cisco

4-Port E1 Port Adapters supporting G.703 and G.704.

The Cisco 4-Port E1 G.703 Serial Port Adapters (PA-4E1G) provide up to four E1 synchronous

serial interfaces, which are compatible with and specified by G.703/G.704. The port adapter

network interfaces provide a connection between standard serial interfaces such as V.35 to

telephone lines or post, telephone, and telegraph (PTT) networks. Each port adapter interface

operates in full-duplex mode at E1 (2.048 Mbps) speed.

The port adapter interfaces do not operate in the data-terminal-equipment (DTE) and data-

communications-equipment (DCE) modes that are typical of data communications interfaces; they

operate with either a line-recovered or an internal clock signal. The default is for a line clock signal

that the interface recovers from the received data stream. The interface can also operate with an

internal clock signal. The port adapter generates the internal clock signal; the interface does not

use the motherboard or system clock.

The Cisco 4-Port E1 G.703 Serial Port Adapters provide framed and unframed service access,

E1 (2.048 Mbps) line speeds over unbalanced 75-ohm or balanced 120-ohm cable, with 15-pin,

D-shell (DB-15) receptacles on the port adapter. Two unique port adapters support either balanced

or unbalanced modes, not both (Figure 1).

Figure 1. Cisco 4-Port E1 G.703 Serial Port Adapters

Applications

The Cisco 4-Port E1 G.703 Serial Port Adapters provide up to four E1 synchronous serial

interfaces, which are compatible with and specified by G.703/G.704. G.703 is the Consultative

Committee for International Telegraph and Telephone (CCITT) standard for transmitting voice over

digital carriers over an E1 circuit. G.703 provides the specifications for pulse code modulation at

data rates from 64 kbps to 2 Mbps (E1). G.703 service is typically used for interconnecting DCE

such as bridges, routers, and multiplexers and is transported over balanced (120-ohm twisted pair)

or unbalanced (dual 75-ohm coaxial) cable supported by this port adapter. Whether the G.703 is

balanced or unbalanced depends on your geographic location and the carrier that supplies the

service. Balanced service is the most common around the world except for England and Holland.

G.704 is the framing specification for G.703.