Phone System

The Labor's telephone System lately got an asterisk system as addition. Since installed it grew more and more sophisticated, so it was time to document all the features the new system provides.

Popular extensions

Number	Target
1337	Talk directly over the Music speakers
1010	All phones in the basement (none installed yet)
1020	All phones in the lecture ("Vortragsraum") room
1030	All phones in the lounge
1040	All phones in the workshop room (none installed yet)
1111	Conference room

Fun & Testing extensions

Number	Target
700{0..2}	Trash reminders
9710	Will tell you the current unix time

Technical details

Wiring

We have both SIP and analogue phones lying around, so we somehow needed to connect these. Another nice-to-have feature was to being able to talk to the outside world (via ISDN) even when the asterisk Server is not available. Unfortunately, this happens to be the case rather often because the system it runs on has lots of users with uid 0...

At first we connected the analogue phones to a box which can talk ISDN and SIP (a "fritzbox" in this case). The box is connected to the ISDN S0 bus and ethernet. It registers at the asterisk server with a given SIP account and is configured to dial out when a "0" is dialed or the SIP connection fails. Incoming calls on the ISDN line are answered whenever a user picks up the phone.

==========================  ISDN S0 (from phone provider)
  |           |
fritz      asterisk
 box          |
  |           |
==========================  Ethernet