NPSTN → Frequently Asked Questions

Q: What is NPSTN?
A: NPSTN is a private VoIP telephone network for phreaks and telephone collectors. It is very similar to C*NET, the official Collectors' Telephone Network, but it places a larger emphasis on the soundscape in an effort to fully recreate (as best as possible) the sound and feel of the analog telephone network. Furthermore, NPSTN is 100% phreak friendly. While it started off with humble origins in early 2018, NPSTN is no longer small or local. While we maintain a local feel by sticking with 7-digit dialing, we have users in several countries and all over the U.S. NPSTN can also fail-over to multiple Route Table switches around the world for amazing reliability! For more on the history and background of NPSTN, see the NPSTN Docs.
Q: Why are there no country codes on NPSTN?
A: We had a discussion a while back and ultimately decided to follow U.S. 7-Digit-Dialing; this is because most of the members that are a part of NPSTN are in the U.S. and we feel that no matter where people are on the network we can create a better experience by making everything seem more 'local' to the subscriber.
Q: What if I am already on C*NET but want to be a part of NPSTN?
A: Please refer to the NPSTN Docs for specifics. At a minimum, you will need to add a new IAX user to your system to accept NPSTN calls, and you will probably want to add some other stuff, especially if you plan to route calls out to the network.
Q: What if I don't have a 'system' to hook up. How can I attach a regular phone to the network?
A: You can be hosted on the BEechwood4 exchange, or one of our members could volunteer to do the same. Just email admin [at] or pose the question to the mailing list after you join it. You will need either:
  1. a telephone and analog terminal adapter (ATA) Use the Grandstream HT502 or GXW-4008 for Rotary Support,
  2. a Digital IP phone,
  3. a softphone (Software application based Phone) installed on your Personal Computer or Other Device.
Q: My step switch has three-digit dialing so I don't know if that's something that can be configured around in the software or if I have to put in digit-absorbing selectors in my switch.
A: Asterisk can impulse into your switch with any number of digits you like. For example, if one of your NPSTN-assigned phone numbers is 971-4776, you could configure Asterisk to send just "776" to your step switch.
Q: Does Asterisk support rotary pulse dialing, or does one need tone->pulse converters on his switch?
A: Yes, Asterisk supports pulse dialing, It's just the hardware you connect to Asterisk that may not support pulse dialing. Zaptel/Dahdi hardware made by Digium can understand pulse dialing. There is a parameter that needs to be set in /etc/zapata.conf: pulsedial=yes If you just want to connect one or two Telephones to Asterisk and don't have a Step or other electromechanical switch then Grandstream HT502 ATA's will work for you, If you need 8 Telephones then the Grandstream GXW-4008 Will work for you. Most Grandstream ATAs understand pulse dialing as of the time of writing Jan 26, 2019.
Q: What do you recommend as a minimum (and cheapest) hardware complement for the Asterisk interface to an Electromechanical Switch?
A: What I have learned so far is this: For the lowest possibility of hassles, get a new board from Digium. They'll stand by you every step of the way, from talking with you to determine what board you will need, to helping you get it installed properly to standing behind it if something goes wrong. Another brand new FXO and FXS cards are manufactured offshore, but sold by US companies. The one with which I've had dealings is Voicetronix. My only issue in dealing with them is that they are located in Australia, so it's a bit difficult to synchronize their business hours with your free time. They definitely know their stuff, though, and were able to work with me to get some nasty echo problems cleared up. DiaLogic has a whole slew of products that will work with Asterisk, but I've not heard how well they work There are clones of Digium's Zaptel cards that are made in Asia. They are cheap and generally work well. But they have no tech support. You buy these if you're skilled at installing the Digium cards. And there are others, all listed at Lastly, there is the used market. I sold my Voicetronix card on eBay, and the guy who bought it from me was quite happy with the card, as well as the price he paid. If you go that route, the usual eBay precautions apply: Deal with only those people who have perfect or almost perfect records as regards positive feedback. If you want additional peace of mind, buy shipping insurance. Do a search on TDM400P or X100P, depending on whether you want the FXO or FXS card. (Again, consult the website in the previous paragraph to see which is which).
Q: I have several computers and have been considering loading Linux on one of them, and I have a broadband connection. What else would I need to participate in NPSTN, and what would I gain?
A: You would need an Ethernet port on that computer, either on the motherboard or as a card. And you would need a card in your PC that would serve as the physical interface between your computer and your Telephones/Switches.
Q: Should I use SIP or IAX to connect to the NPSTN?
A: Either should work well, but IAX is strongly recommended. IAX is the simplest to set up, especially if your computer is NATted, i.e., using private IP space. The NPSTN verification subroutines rely on IAX trunking.
Credit to the Collectors Network for supplying a basis for this FAQ documentation.