I
use this function in my PSTN to VOIP gateway above.
DISA
(Direct Inward System Access)
allows you to dial in
from outside to the Asterisk switch (PBX) to obtain an "internal"
system dial tone. You can place
calls from it as if they were placed from within.
Normally you can do this via the Digital Receptionist and enter the unannounced option number known only to selected callers.
The
caller enters his/her password, followed by the pound sign (#). If the password
is correct, the user is then given system dial tone on which an external call
may be placed.
This
type of access has SERIOUS security implications, and GREAT care must be taken
NOT to compromise your security.
The
example below is how I have implemented my DISA.
In
my "MyMenu" that says, “Hi, you have reached the Sharif’s
household. Press 1 for Ben, 2 for
Rohani, 3 for Norsurya etc…” I have created an extra option – option 4
(best if you use a few digits) that has an "Action" of "Custom
App", which reads, "custom-pstn2voip,s,1".
Then
in extensions_custom.conf, I have added (do this towards the end
of the file).
[custom-pstn2voip]
< -- you can name it to whatever you like
exten =>
s,1,Answer
exten =>
s,2,DigitTimeout(5)
exten =>
s,3,ResponseTimeout(10)
exten =>
s,4,Authenticate(12345678)
exten => s,5,DISA(no-password|from-internal)
Change
"12345678" to whatever digits you want your "DISA password"
to be.
The
above is one way of doing it (the hard way). The easier way of doing it is through freePBX - see below.
Those
using TRIXBOX with freePBX as the User Interface will be able to configure DISA
from freePBX without having to do the above manual configuration. The same thing can achieved through freePBX as illustrated in the
screenshot below.
I
have populated the various fields thus:
·
DISA
name:
PSTNVoIP (This
is the name I gave to this application)
PIN: 1234 (or whatever you think is appropriate.
This pin number will be asked when you want to use this service)
Response
Timeout:
10 (time needed for a response from the you in seconds)
Digit Timeout:
5
The
rest you can leave at the default value.
When
you set up your digital receptionist, in the DISA dropdown selection, simply
select PSTNtoVOIP as your DISA application.
If
you are using this method, there is a slight catch. When you choose the DISA option to call a number, you will be
greeted with “Please enter your password followed by the pound key” and
immediately you will get a dial tone. You
may start dialing the password followed by # followed by the telephone number.
E.g.
If you have chosen to have a password e.g. 12345, and the number you wish
to dial is 0292345678, you must dial the number thus: 12345#0292345678 without waiting for another
dial tone, otherwise
it will not dial out correctly and you will be wondering what happened. I hope this will be fixed up soon.