About Sip Trunking - Cisco Small Business SPA2102 Administration Manual

Configuring Voice Services
SIP Trunking and Hunt Groups on the SPA8000
Cisco Small Business ATA Administration Guide

About SIP Trunking

The SIP Trunking feature allows a traditional PBX to seamlessly migrate from
PSTN service to VoIP service over a broadband link. The SPA8000 offers up to
eight telephone lines to the PBX.
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PBX System
The SPA8000 offers four trunk groups, numbered T1, T2, T3, and T4. A SIP-based
voice service with an ITSP can be configured on each trunk group with a distinct
phone number. Each of the eight SPA8000 lines can be configured either as a
standalone line, as in a classic ATA FXS port, or as a trunk line that is associated
with a trunk group.
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Inbound calling: A trunk group offers a single number for callers to call into the
small business, with the capability to programmatically ring one or more trunk
lines.
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Outbound calling: When a PBX phone makes a call, the PBX selects one of the
available trunk lines. The trunk line assumes the Caller ID of the trunk group.
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PBX System
SPA8000
Integrated
Access Device
Internet ITSP
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