About Sip Trunking - Cisco SPA2102-AN - Single Port Router 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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