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Cisco ICS 7750 System Description
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Chapter 8 Features of Other Compatible Cisco Devices
DT-24+ and DE-30+ Digital Gateway Modules
DT-24+ and DE-30+ Digital Gateway Modules
The DT-24+ and DE-30+ digital gateways are modules that are used with
Cisco CallManager to connect Cisco IP phones to the Internet. The DT-24+ or
DE-30+ module is installed in a 32-bit Personal Computer Interface (PCI) slot in
a PC desktop or server chassis.
Digital gateways differ from analog gateway products in that they support digital
ISDN features including Direct Inward Dialing (DID) and caller ID. These
features allow outside callers to dial directly to a particular user without going
through an attendant (operator). In addition, digital interfaces usually provide a
more economical interface choice when the number of trunks exceeds six to eight
channels.
When more than one digital gateway is needed, the additional gateway can be
treated as a separate gateway or aggregated with the other gateways as a common
pool of channels. Any number of digital gateways can be installed in a network,
and the number installed in a PC is limited only by the number of available slots.
Digital gateways communicate with Cisco CallManager, which allows the
implementation of supplementary services such as holding, transferring, and
forwarding of outside calls. Also, with proxy signaling provided by the
Cisco CallManager, the digital gateways are fully compatible with H.323 V.2.
DT-24+ Digital Gateways
DT-24+ digital gateways provide the interface to the PSTN or existing PBX
systems through T1 ISDN Primary Rate Interface (PRI) interfaces. DT-24+ digital
gateways support up to 23 simultaneous channels of VoIP packet to
circuit-switched adaption, G.711 encoding (A-law or mu-law), dual tone
multifrequency (DTMF) detection, generation, and signaling, and line echo
cancellation. Twenty-three simultaneous channels of G.723.1 encoding/decoding
are also supported.
DT-30+ Digital Gateways
DT-30+ digital gateways provide the interface to the PSTN or existing PBX
systems through E1 ISDN PRI interfaces. DE-30+ digital gateways support up to
30 simultaneous channels of VoIP packet to circuit-switched adaption, G.711