Because the tutorial has already been written. In fact, Ward Mundy just wrote another tutorial in the last week…
The most important advice was to never open port 80 or port 5060. “If you can access TCP ports 22 (SSH) and 80 (HTTP) and TCP/UDP port 5060 (SIP) of any of your Asterisk® and FreePBX-based servers anonymously from the Internet, you’re either nuts or rich.”
There’s been an OpenVPN tutorial on the PIAF Forum for the last four years. Let me Google that for you…
Actually let me hopefully diffuse this. To my knowledge H.323 was the first ratified Voice of packet technology. Certainly it wasn’t IP. We were doing VoFR Voice over Frame Relay for paging system backhaul as early 1991. I think the product was a Micom Forerunner. On a 64k clear channel (no robbed bit signalling, single DS-0) point to point DDS service we used an 8k ADPCM (adaptive compression PCM) CODEC to squeeze a shocking 9600 baud maint. terminal, an order wire line (major props to anyone that knows what this we except Dicko) and 5 paging trunks.
The funny thing is the major problem was DTMF recognition down the trunks for voice mail and digital pagers. It was solved by the vendor with what I believe was the first hard, out of band DTMF extender. This thing was an ugly beast. It sat after the center tap xfer/relay on the 600 ohm 2 wire side of the hybrid. It was a field mod, you had to cut traces (techs could actually fix things back then not just whine and open tickets) and insert this board. It contained 8 analog notch filters for the DTMF fundamental row column tones to pull the DTMF out of the channel. The filters were pretty poor they drifted and were only about 24-30db deep so sometimes just enough DTMF would get through to screw the pooch.
Anyway once again I digressed. A DTMF detector sat in front of the filter. The data bus of the decoder went to some inexpensive uPU that put the data in a little message and send it to the far end where is was re-encoded.
So much has changed but has not. I would call digital voice a 60’s technology (North American Digital Hierarchy DS-X technology, TDM), compression over TDM, 70’s, Packet voice 80’s, Voice over X 90’s, softswitching 2000’s
Sometimes I am blown away I have been in the industry since the 70’s and am still relevant today. It was a great time to be in tech.