[asterisk-users] allowing call every 15mins

[Luki]

> GotoIfTime can help you here, but it'll be a little messy:

That should be a sign that GotoIfTime is not the right tool to use here.
Instead try:

exten => 1,1,Set(M=${TIMESTAMP:11:2})
exten => 1,n,GotoIf("${M}" = "00" | "${M}" = "15" | "${M}" = "30" |
"${M}" = "45"?good_timing)
exten => 1,n,VoiceMail(100 at default)
exten => 1,n,Hangup
exten => 1,n(good_timing),Dial(SIP/techsupport)

You get the idea... but I agree, why on earth would you want to do
that? We only provide 6.7% tech support?!

--Luki