Asterisk: The Definitive Guide, 5th Edition

Chapter 11. PBX Features, Including Parking, Paging, and Conferencing

I don’t believe in angels, no. But I do have a wee parking angel. It’s on my dashboard and you wind it up. The wings flap and it’s supposed to give you a parking space. It’s worked so far.

Billy Connolly

This chapter discusses several peripheral features common to business telephone environments. We’ll briefly cover the features.conf file, and then spend a few sections on paging and parking, and finally do a bit of work with Asterisk’s conferencing engine, confbridge.

First up, let’s copy the features.conf file over from the installation directory, and have a look at it:

$ sudo cp ~/src/asterisk-16.<TAB>/configs/samples/features.conf.sample \
/etc/asterisk/features.conf 

$ sudo chown asterisk:asterisk /etc/asterisk/features.conf

features.conf

Asterisk provides several features common to most PBXs, many of which have optional parameters. The features.conf file is where you can adjust or define the various feature parameters in Asterisk.

DTMF-Based Features

Many of the parameters in features.conf only apply when invoked on calls that have been bridged by the dialplan applications Dial() or Queue() using one or more of the options K, k, H, h, T, t, W, w, X, or x. Features accessed in this way are DTMF-based (meaning they can’t be accessed via SIP messaging, but only through touch-tone signals in the audio channel triggered by users dialing the required digits on their dialpads).¹

Transfers on SIP channels (for example, from ...