I don't have freepbx but got this to work with asterisk 1.6.0.26
Create a file called build_buttons.pl and paste following code.
#!/usr/bin/env perl
#
# Extensions
#
while (<>) {
if (m/\[\d/) {
chomp $_;
s/\[([0-9]+)\]/\1/;
print("[SIP/$_]\n");
print("type=extension\n");
print("extension=$_\n");
while (<>) {
if (m/^$/) {
last
}
if (m/^(context|label|vmexten=[0-9]|callerid|mailbox|\[[0-9])/) {
s/\<([0-9]+)\]/\1/;
s/callerid=/label=/;
s/ <\d+>//;
if ( m/context/ ) {
$context=$_;
$context=~ s/context=//;
chomp $context;
}
s/(mailbox=\d+)/\1\@default/;
s/vmexten=(\d+)/extenvoicemail=*\1\@$context/;
print
}
}
}
}
#The rest of this is just hardcoded buttons.
#
# Conference
#
print("[CONFERENCE/1600]\n");
print("type=conference\n");
print("label=User\n");
print("extension=1600\n");
print("context=from-internal-redir\n");
print("\n");
print("[PARK/default]\n");
print("extension=700\n");
print("context=parkedcalls\n");
print("type=park\n");
print("Label=Parked \n");
print("\n");
print("[SIP/VoicePulse]\n");
print("type=trunk\n");
print("label=VoicePulse\n");
print("[G1]\n");
print("type=trunk\n");
print("label=PRI\n");
print("channel=DAHDI/1\n");
print("channel=DAHDI/2\n");
print("channel=DAHDI/3\n");
print("channel=DAHDI/4\n");
print("channel=DAHDI/5\n");
print("channel=DAHDI/6\n");
print("channel=DAHDI/7\n");
print("channel=DAHDI/8\n");
print("channel=DAHDI/9\n");
print("channel=DAHDI/10\n");
print("channel=DAHDI/11\n");
print("channel=DAHDI/12\n");
print("channel=DAHDI/13\n");
print("channel=DAHDI/14\n");
print("channel=DAHDI/15\n");
print("channel=DAHDI/16\n");
print("channel=DAHDI/17\n");
print("channel=DAHDI/18\n");
print("channel=DAHDI/19\n");
print("channel=DAHDI/20\n");
print("channel=DAHDI/21\n");
print("channel=DAHDI/22\n");
print("channel=DAHDI/23\n");
buttons.cfg only has this line
#exec build_buttons.pl < /etc/asterisk/sip.conf
