Plain Old Telephone Service and VOIP Comms

Here we discuss the similarities and differences from POTS to VOIP data connections, with the positives and negatives of both these alternatives. For those nostalgic for sweet things from the past this can be a lot of fun. Welcome to 56k.

Voice/Data/FAX Communications Going Next Level!


Both POTS (Plain Old Telephone Service) and VOIP (Voice Over Internet Protocols) have as their primary function to serve people's voice communication needs.  However where you can get voice comms you can also get a data stream to send files and messages thorough.  We are very lucky as there is an uncompressed VOIP protocol that uses an uncompressed stream.  This means that, theoretically, you can get the same speeds as old-school dial-up speeds through a VOIP modem, often connecting at 48.8 kbps using the 56k v.90 and v.92 communications protocols.  It is currently not possible to connect at the full 57.3 (56k) speeds because one end of that modem transaction needs to be fully digital to handle that, such as an ISDN line (Integrated Services Digital Network).  ISDNs have two channels of 64 kbps throughput, so if you really know what you're doing you could lease an ISDN line and host two 56k dial-ins from the one ISDN connection.  But back to POTS and VOIP, these technologies are exceptionally cool, allowing comms in times of war, natural disaster, or other horrific and unforeseen events when the Internet infrastructure is under attack or a catastrophe of some sort.  For an average person with a POTS or VOIP line you can expect, under optimal conditions to get 48.8 kbps.  On less than optimal lines, such as my own, I can easily get 19.2 kbps, but I use it for messaging and not transferring files so it works for me.  My setup is rather sweet: I have an external 56k v.90 and v.92 modem by US Robotics that I connect into my Ubuntu/Linux box via an DTECH FTDI USB to Serial cable.  The cable is expensive at around $30 CAD from Amazon but it is really quite cool, lighting up with different colours to indicate whether the device is primarily sending or receiving data at the moment.  If I want 28.8 kbps to 33.6 kbps speeds I can bring a Ubuntu/Linux box downstairs and hook it right into the house's POTS connection.  FAXes also work over both POTS and VOIP connections.  That POTS works with FAXes is a given, as its obvious, but working over VOIP isn't that expected, but with an uncompressed VOIP line you can treat it as any old school POTS connection.  It works quite well, surprisingly indeed.  I use the GrandStream HT802 VOIP ATA (Analog Telephone Adaptor) for the hardware, and as my service provider, who by the way has amazing rates—the best out there.

FAX Modems

Most modems that you can easily purchase now-a-days can also communicate with FAX protocols, that allow you to both send and receive FAXes from your modem.  If you are receiving FAXes then this is a much better option than using a dedicated FAX machine.  I have actually received advertisements on my old FAX machine that would give information about various retailers, home repair people, and un-requested garbage.  Using a FAX modem with the appropriate software you can have your FAX modem save the FAXes in some sort of format that allows you to pick and choose what you want and what you don't want.  It saves on printer paper and is far less annoying.

Signing up With With a Nod to offers us some free service in return for advertising their offerings.  Their offerings are being advertised to you not for the fact that we get money back from sending you to our affiliate link, but rather that we totally believe in this company for providing unsurpassed quality, reliability, and having very low phone rates.  You can call anywhere in Canada and the USA for about one cent per minute.  Residential and business options are available.  Residential costs a flat rate of about $7 USD, while Business use is a per-minute offering at 0.09 cents per minute.  Our affiliate link will be posted below this text shortly.  You will need to buy an ATA (Analog Telephone Adaptor) to use' services, which cost about $50 USD for the hardware and built-in software.  If you are looking to reduce your phone bill drastically with a small initial investment then this solution may work well for you.


My recommended setup is exactly what I have right now which work perfectly for me.  I'll post the name of the item with the Amazon link beside it, and will use the American system as there are more people in the USA than Canada, so it would be more relevant to most people.

The USB-to-Serial Cable:

The US Robotics External v.90 v.92 POTS serial modem:

The extremely high quality telephone cable (RJ-11): Phone Service: (Select G.711 Uncompressed Audio for the codec)

Ubuntu GNU/Linux:

The two cables go for a good price on Amazon, however the USR modems can be found at a large discount from, even a third or a quarter of the price of one from Amazon, so its good to shop around.