Northern UTA220/UTA220k manual Isdn Channels, Channel Data Service

ISDN

The TEI is used to identify the terminal device. In most applications, the network switch automatically assigns a TEI to the TA when the connection is established; otherwise, you must enter the TEI before connecting to the network.

If your switch permits it, the UTA220 allows you to use one SPID and one TEI on simultaneous calls. AT&T switches allow two calls per SPID. With this support you can configure two or more ports to share a DN.

Note: To use this feature, configure each port with the same SPID and DN, enable one port’s TEI, and disable the TEI on the remaining port(s).

The UTA220 also allows you to use multiple DNs on the same

SPID if your switch supports it. NT switches support up to four

DNs per SPID.

Note: To use this feature, configure both ports with the same SPID and different DNs, then enable one port’s TEI and disable the other’s.

ISDN CHANNELS

As previously mentioned, there are three channels available on the ISDN Basic Rate Interface: two 64 Kbps B-channels and one 16 Kbps D-channel. The B-channels are the primary means of carrying user information, whether voice or data. Voice data must be sent on a B-channel. The B-channel also provides the most efficient path for data communications, since it has four times the data capacity of the D-channel.

The D-channel is the control channel between the TA and the network switch. It is used mainly for exchanging signaling messages with the switch, to perform functions like setting up and releasing calls.

Note: The UTA220 supports only data calls.

B-Channel Data Service

When a B-channel data call is placed, the switch allocates a free B-channel between the TA and the remote DCE (e.g., the TA at the other end of the ISDN link). This B-channel acts like a bit-pipe between two network users, operating synchronously at 64 Kbps. In most cases, the ISDN network does not know about the format of the data sent on the B-channels.

There are several ways to use the B-channel to pass data. In the “clear channel” mode, data from the DTE goes directly onto the B-channel. However, to use this mode, your DTE must also operate synchronously at 56 or 64 kbps.

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