Switching to VoIP

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Legacy Endpoints

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Private hunt groups are more advanced ring groups. Like the PSTN hunt groups, pri-

vate hunt groups allow calls destined for a phone that is currently unavailable to roll

to another channel—usually another phone. Depending on why the phone is

unavailable to receive a call, the hunt group may have a different type:

• Sequential hunt groups seek the next available channel from a list.

• RNA (ring no answer) hunt groups roll the call to the next channel when there’s

no answer on the first phone, in addition to when that first phone is in a call.

• Simultaneous hunt groups may ring all phones simultaneously, like a ring group,

but only when a “lead phone” is busy on a call.

Most PBXs support some combination of ring groups and hunt groups.

The group of analog phones in most homes is not a ring group, but

rather an electrical aggregate: a parallel cluster of analog PSTN end-

points. In an all-analog residential setup, all phones ring at the same

time, like a ring group. But unlike a ring group, the phone that

answers the call doesn’t become exclusively connected to that call.

Project 4.2. Simulate a Simple Key System

with a Ring Group

What you need for this project:

• Asterisk

• X100P interface card

• Cisco SIP 7960 IP phone (or similar)

• Grandstream Budgetone 101 IP phone ...