When I bought my house in 2013 I had planned on installing a phone system. Not just a bunch of phones, but a PBX. Why? Well, why not? Phones were evolving into little network devices, with Ethernet replacing silver satin. Surplus IP phones were showing up on eBay. I was fairly aware of the concepts behind VoIP PBX systems, and there was this open source software called Asterisk. But the reality is there’s not much of a need for a dedicated home phone anymore, especially when my iPhone did WiFi calling through T-Mobile anyway. In fact only about 25% of American households have a wired phone these days, and I’ll bet nearly all of them have it as part of a “bundle” with TV and Internet service, not because they want a wired phone. The need wasn’t really there, and I had just paid out a very large down payment on a mortgage. So I didn’t bother either. As always, a little ahead of the tech curve.
I knew about Asterisk thanks to the amateur radio tie-in called AllStar. AllStar (aka ASL) is what makes a lot of analog linked repeater networks work, including the Colorado Connection and the Ski Country Amateur radio club’s K0RV repeater. Way back in 2014 I proposed the club migrate off the all-analog links to an AllStar based system (using 3.0 GHz data radios) to improve the quality of the audio and enable some new features like “voting,” a process where the receivers are all listening and reporting signal strength back to the main hub. The hub then uses the best receiver to transmit. Back in 2014 the software was fairly difficult to configure. You had to understand repeaters and how they function but you also had to understand PBX phone systems and be very comfortable with the Linux CLI.
That was then. More properly, that was ASL 1.4. Back then I tried to get AllStar running on an Intel PC. The build was tedious and I never really got the concept enough to figure out what was wrong. Worse still, the community support was like the bad old days of Linux, where you had to make sure you checked every poorly written howto and scoured the repeater-builder.com forums before asking for help. And the fixes were usually some misspelled cryptic command, or a commented out line that should have been uncommented. So the club’s repeater upgrade languished and I turned in my repeater technician badge.
This is now. We hams lost the 3 GHz spectrum so now the repeater network runs on a sliver of the 5 GHz WiFi band. The links are active, but have changed from 3 different repeaters to a single high power transmitter and 4 different fill-in voting receivers. The Raspberry Pi computer is powerful enough to run AllStar easily. One of the club members has an AllStar node that we can use with our own devices to link over the Internet. More importantly, the Amateur Radio Digital Communications (ARDC) foundation provided a grant to do a ground-up rewrite of AllStar’s core, improve the user interface and basically bring it up to modern standards. This makes ASL 3 extremely easy for amateurs to set up nodes and link them over the Internet. Not quite plug and play, but also not at all frustrating. If you’re familiar with Debian Linux and have an afternoon you can probably get a node going. The developers have distilled everything into a pre-built image file that just gets written to an SD card. Set up a few configuration files and enter your information and done.
There’s also been a lot of progress in making digital voice modes interoperable, and a pretty easy way to link digital voice repeaters with AllStar, using software called DV Switch. This software plus a few hardware encoder-decoder chips, will take D-Star, DMR or any amateur digital voice protocol and convert it to AllStar (or any other DV protocol). I’ve been wanting to tie the K0RV-DV repeater into the club’s primary repeater for some time but never really got much traction to finish the job. Too many memories of ASL 1.4 I guess. But over the winter our primary transmitter on Sunlight mountain lost the power amplifier, so the usual 150 Watts output was down to 40 or so. That meant I could no longer hear the repeater at home. So I was stuck with either extremely poor or no signal, or Echolink. That’s when I started looking at AllStar again.
It turns out there are excellent apps for iOS (RepeaterPhone) and macOS (Transceive) that can access the AllStar network. Just enter your callsign, registration number, password and that’s it. You’re on AllStar with great quality first-generation audio right on your phone. For most of the winter and spring this worked well enough while I was doing other things with radio.
Over the summer I started re-examining what it might take to use my Kenwood TH-d75 on the club network using the D-Star repeater. I also picked up an Icom IC-7100 for a mini camper van project and since it has D-Star as well I wanted to get more use out of my repeater. So I began investigating options, and discovered ASL3.
I also found out that I’d need more hardware, in the form of two AMBE 3000 chips. This chip is how D-Star, DMR and other digital voice (DV) modes are so spectrum efficient. The AMBE chip processes audio streams and turns it into a 4800 bps data stream for transmission over radio. Why two? Well, because repeaters are full duplex devices so you need to decode the incoming stream, convert it to work over ASL and then re-encode the outgoing ASL3 stream to go back to the D-Star repeater. Unfortunately the chips seem to be out of stock much of the time, so I waited and watched until the company did another production run.
In the meantime I had an AllStar node working, could connect via software and all seemed to be good. But then I began wondering about how I might add an IP phone to ASL3. There has been a lot of progress on that front as well. In 2014 IP phones weren’t all that friendly. Some programming was possible from the keypad but if you really wanted to set them up properly you needed to set up a TFTP server on your network and create a bunch of configuration files for each unit. TFTP = Trivial File Transfer Protocol, and it does what the package says: It will send a file to a client without a lot of frills. The phone boots up and starts broadcasting its MAC address. The TFTP server hears the MAC and sends the corresponding config file. Setting up a phone is a process of rebooting, troubleshooting, rebooting, troubleshooting etc until it works. These days are much better. The phones have a lot of configuration options on their screens, but even better, they have web configuration! So just find the IP address of the phone and log in through Safari. Super easy! In no time at all I had a Grandstream WP826 SIP phone connected to my ASL3 node and was talking to Chuck, N0NHJ over the club repeater.
Pretty slick. But some might say “that’s not really radio.” I get it. I feel like that too. So I came up with a way to use ASL3 to transmit out on a regular shack radio, the opposite of what most hams are doing with AllStar. Most hams have a low power HT they use with ASL3 to bridge nodes and repeaters across the Internet. This will do the opposite (but only in my home network), so I can carry the SIP phone around the house but use a fixed radio with high gain antennas and more power out to get into repeaters. But not right now because of course I need another adapter that won’t arrive until Tuesday.
Next: Homebrew Home Phone
Eric - GREAT explanations! Looking forward to future installments! I gotta get Transceive!