sig_analog: Add fuller Caller ID support.

A previous change, ASTERISK_29991, made it possible
to send additional Caller ID parameters that were
not previously supported.

This change adds support for analog DAHDI channels
to now be able to receive these parameters for
on-hook Caller ID, in order to enhance the usability
of CPE that support these parameters.

Resolves: #94
ASTERISK-30331

UserNote: Additional Caller ID properties are now supported on
incoming calls to FXS stations, namely the
redirecting reason and call qualifier.

configs/samples/chan_dahdi.conf.sample

@@ -572,6 +572,15 @@ context=public
 ;
 usecallerid=yes
 ;
+; NOTE: If the CALL_QUALIFIER variable on the channel is set to 1,
+; the Stentor Call Qualifier parameter will be sent for Caller ID spills
+; using the Multiple Data Message Format (MDMF).
+; This is used by capable Caller ID units to activate the
+; "LDC" (Long Distance Call) indicator.
+; This variable is not automatically set anywhere. You are responsible
+; for setting it in the dialplan if you want to activate the indicator,
+; and you must have compatible CPE.
+;
 ; Type of caller ID signalling in use
 ;     bell     = bell202 as used in US (default)
 ;     v23      = v23 as used in the UK