11  PSTN to VOIP Gateway

Note:  If you are using TRIXBOX, the following instruction may not apply as you can create DISA from FreePBX option without having to resort to the manual configuration below  – see DISA, 

Now that the SPA-3000 has been set-up to accept PSTN, TRIXBOX can be turned into a PSTN to VOIP Gateway.  You will not need a SPA-3000 if you have an FXO card installed. 

I need such a gateway because I often have to call overseas from my office.  Needless to say, we don’t make private overseas calls from the office phone.  I overcame this by calling my Asterisk box from the office and when it answered, I can then use asterisk to call overseas. 

I accomplished this through DISA – I have resorted to this manual method because in the initial release of Trixbox, DISA did not work, as I would like it to. This has since been rectified 

To do this, I manually edit the extensions_custom.conf, by adding the following entries at the end of the file, 

[custom-pstn2voip]

;  I use this to call VOIP from PSTN

exten => s,1,Answer
exten => s,2,DigitTimeout(5)
exten => s,3,ResponseTimeout(10)
exten => s,4,Authenticate(my password)
exten => s,5,DISA(no-password|from-internal) 

I have Digital Receptionist answers all incoming calls (refer to Digital Receptionist in the previous section). 

In the previous section I have 5 options in Digital receptionist e.g. Press 1 for Ben, 2 for Rohani, and 3 for Nosurya. I did not announce the 4th option as I use it for DISA and is only known to me, besides, it requires a password. 

For option 4, I chose the radio button next to Custom App.  In the custom app field I entered custom-pstn2voip,s,1 

When 4 is pressed, followed by the # key, during the announcement, the digital receptionist will ask for a password.  On entering the correct password, the one defined in the example above, a dial tone will be heard.  At this stage, you can start dialling the number you wish to call. 

Option 5, (which I have changes to the letter ‘t’, for timeout) is invoked if the caller does not select any option or if the DTMF tone is not recognised.  This option can be directed to a Ring Group or to a human receptionist if you are using Asterisk in a business environment.