Tech Help PART TWO

Cordless Phone Range


Numbers are very important to most human beings, especially men.

The male homo sapiens likes to know that his car has more horsepower, his stereo has more watts, his PC has more RAM, his satellite receiver has more channels, his TV has more inches... than the guy's next door.

With cordless phones, range is the important number, even though it's almost always unimportant.

Most people seldom take a cordless handset more than 20 feet from its base. 100 feet will take you far beyond most homes, and a football field is just 300 feet long... yet lots of people are asking for phones that can go a mile.

It's tough to find a cordless with that kind of CONSISTENT range. The EnGenius cordless phones have the longest range of any cordless phone that can legally be used in the US, and their range can be 1/2 mile to 5 miles or even more, depending on conditions.

That brings us to an important point. Back when gasoline was scarce (the first time, not because of Hurricane Katrina), lots of car commercials bragged about gas mileage, and then weaseled-out by stating that "your mileage may vary." It's that way with cordless phones, too. The advertised ranges are seldom equaled in the real world; and the same phone may behave very differently in two places, or even in the same place on two different days.

You may hear about cordless phones that can reach 30 miles or more. They are illegal to use in the United States.

SOME BASIC SCIENCE: With all else being equal, radio transmissions with higher frequencies, have shorter range than lower frequencies.

That's why UHF (ultra high frequency) TV stations don't reach as far as VHF (very high frequency) TV stations; and why FM stations (transmitting in the 88 - 108 megahertz band) don't reach as far as AM stations using the 540 - 1600 kilohertz band. Don't believe advertising claims about 2.4GHz phones providing extra long range.

Many phone makers now offer cordless phones that operate in the 5.8GHz band. This new higher frequency is not likely to provide important performance advantages.

In 2002, in an interview for TWICE, a consumer electronics trade magazine, VTech's cordless product manager Brad Pittmon said, "The market needed something new. The 5.8GHz frequency will take the positioning previously occupied by 2.4GHz DSS as the early adopter product, leaving 2.4GHz to the mass market. We are now gearing our 2.4GHz products to women and family users as opposed to the tech savvy."

On the other hand, Panasonic's consumer phone product manager Wayne Borg told AbleComm that 5.8GHz has a couple of real advantages: it won't pick up interference from microwave ovens, and won't cause interference with wireless networks or security systems.

The situation got more complicated in 2006, with the introduction of "DECT 6.0" cordless phones that operate in the 1.9GHz band.Unlike 2.4Ghz cordless, DECT 6.0 phones are virtually immune to household interference, and vice versa. If you have a wireless computer network in your home, DECT 6.0 won't disrupt your internet use.

Almost any modern cordless phone, except for obvious junk, can provide decent voice quality a hundred feet from the base -- more than enough for most users.

Cordless phones are generally able to maintain an existing conversation at a greater distance than they are able to start a conversation, and can ring at greater distances than they permit talking.

When you move around while using an analog cordless phone, near the end of its range, you will probably hear a "fluttering" sh-sh-sh sound.

In the same conditions, while using a digital phone, you will probably hear clicks.


  • Near the range limit of any cordless phone, slight movements and changes in position can make a big difference in performance. If you put your head between the handset and the base, you may lose the signal, but if you turn to let the handset be in line-of-sight with the base, it may work just fine.

  • Dense vegetation limits range, and wet leaves are worse than dry leaves.

  • Broadleaf trees (hardwoods such as oak, maple and birch) limit range more than conifers (softwoods such as pine, fir and cedar).

  • If you can get the base up high, you will probably get more range.

(last update 30 MAY 2007)

About trunks

This section is optional. If you're not a phone geek, you can skip it.

The telecommunications business frequently has very poor communications, and the term "trunk" is a perfect example. Its origin in telecom is uncertain. It may relate to a tree trunk, which is larger than the branches that come out of it. Some transportation routes apparently use the term for that reason. India has a Grand Trunk Road and Canada has a Grand Trunk Railway (not to be confused with Grand Funk Railroad). The term may also come from the elephant kingdom. An elephant's trunk is much thicker than a telephone wire (and much bigger than a human nose).

  • Sometimes a trunk means the same thing as a phone line, but sometimes it doesn't.

  • Some phone systems, particularly large PBXs (Private Branch Exchanges), use "ground start"lines (often called trunks) to signal the central office that you want dial tone by momentarily connecting the “tip” side of the phone line to ground. This is done to avoid "call collision" or "glare," the condition when you pick up the phone to make a call just as a call comes in, but before ringing starts, and two people are confused.

  • A "trunk cable," naturally, has nothing to do with trunks. It’s usually a pre-terminated copper or fiber-optic cable, often with multiple connectors on each end, ordered to a specific length, typically for use in a data center for connection between two equipment cabinets or racks, where cable distances are reasonably predictable and can be easily determined. (Thanks to Siemon for the information in this paragraph.)

  • A T1 line (or T1 trunk) can provide 24 conversations (or data transmission paths) using two pairs of wire. It is commonly used to connect several offices of one company, or to allow a business to connect directly to a long-distance provider, without passing through the local phone company’s facilities.

  • A SIP trunk is the 21st-century replacement for a T1 trunk, and may be much less expensive and provide additional features such as caller ID, call forwarding, call blocking, etc. It is usually provided with DID (Direct Inward Dialing) service and can also be used for outgoing calls.

  • A Private Branch Exchange ("PBX") is a smaller version of the switching exchanges used in phone company central offices, and is installed at a business to provide both internal intercom calls, and to connect to the outside world.

  • In this website, we use "phone" to mean an individual telephone instrument, the thing you talk and hear with, and "line" to mean a circuit between your place and the company that provides your phone service (maybe one of the Bell companies). In PBX lingo, a line is called a trunk and a phone can be called a line, or an "extension."

  • In the VoIP phone service business a phone line may actually be a package of as many as eight lines (i.e., eight phone numbers), or maybe even more.


When diagnosing a malfunction, test every piece of hardware that's involved. You'd be surprised at the things that can be improperly manufactured, inadequately tested, or ruined by human contact.

We once installed a phone system, and the door intercom wouldn't work. We replaced the door speaker, and then the intercom module, and were about to replace the entire control unit, when we decided to check the cord that was plugged into the intercom module. That stupid $4 cord -- which had no right to be defective -- had caused the problem. It wasted our time and annoyed our customer. We'll remember it, and you should, too.


Anything can be made wrong, or messed up. Things that people touch are more likely to break than things that don't get touched. Wire outside a wall is more likely to have problems than wire inside a wall. Phone equipment in an active office is more likely to have trouble than phone equipment in a locked closet.

Telephone Biology 101: is Jack male or female?

The little plastic tips on the ends of phone cords are plugs. Plugs fit into jacks.

Connectors that are used to carry electricity or electronic signals or data have gender.

Despite their male name, jacks are female. Plugs are male. Plug and penis begin with the same letter.

That should be easy to remember, but lots of people get it wrong. Some folks talk about "jacking in," instead of "plugging in." Google shows over 50,000 links for the phrase "jacking in." That's stupid.

Lots of electricians call (female) electrical outlets, "plugs." That's even more stupid.

If you don't understand hardware gender, find someone of the opposite sex, get naked, and look in the mirror. Or study Michelangelo's "Temptation and Fall" on the Sistine Chapel ceiling in Rome.

"Modular" phone plugs are made in three standard sizes. The smallest plug, known as 4-position/4-wire, is used for handset cords. The middle-size plug is the most common. It has six positions, and either two, four, or six wires. It is used for most line cords, for connecting phones and other devices to phone jacks. The largest plug, with eight positions and eight wires, is usually used for LANs (Local Area Networks) and sometimes for phones.

Power & protection

(1) DON'T DON'T DON'T try to save a few bucks by skipping surge protection. Your phone system can get fried by high voltage coming in from the power line or from a phone line, or even from an outdoor phone jack, or wire connecting a phone or paging speaker in another building. Surge protectors vary greatly. Don't think that a lump of plastic you scooped up from a bin at the 99-cent store will do the job. You're investing a lot of money in your phone system; and if it dies, the disruption will be annoying and expensive. Your warranty will not provide a free repair on fried equipment. Good power line protectors cost $30 and up, and usually come with insurance to pay for any damage that isn't protected against. We sell power line protectors and protectors for phone lines (up to 25 lines in one module). 

(2) We use and sell computer-type UPSes (Uninterruptible Power Supplies) which are easy to install, come in a wide range of sizes, and can provide power for both a phone system and a voice processing system. We can help you figure out the proper model to keep your system going for the desired length of time. NOTE: In a business, if you don't have back-up power for your computers and lights, there's probably no point in having back-up power for the phone system, because probably no one will stay in a dark office to answer the phone. However, if you have a voicemail system that normally takes messages when the office is closed, back-up power is important.


(3) During a power failure, with no back-up power supply, some phone systems allow one or more standard phones to operate, but with no intercom, lights or system features. An internal battery will maintain your programming for several days.

What does "hybrid" mean?

Traditionally the word "hybrid" was most commonly used in biology, to indicate a plant or animal that was developed by cross-breeding (combining) two different plants or animals.

Hybrids have been in the news a lot recently, with the term applied to cars that can run on both gasoline and electricity.

Back in the 1980s, Panasonic introduced the first hybrid phone systems.

Traditionally, phone systems were available in two general types. The key system used multi-line phones and the PBX (Private Branch Exchange) used single-line phones. Panasonic hybrids could use either type of phone.

The newest Panasonic KX-TDA, KX-TDE and NCP phone systems have taken hybridization to a new level. In addition to combining the features of both key systems and PBXs, they can also use both conventional phone wiring and Internet Protocol (IP) networking to connect the phones.

They are also hybrids in another sense: their ability to use both corded and cordless phones.


Telecommunications terminology has long been confusing, and it's getting worse. Terminology used by equipment manufacturers and service providers can be inconsistent and ambiguous. We'll try to help you understand.

  • All IP phones are VoIP phones.

  • All VoIP phones are IP phones.

  • All SIP phones are IP phones.

  • Therefore, all SIP phones are VoIP phones.

  • However, not all IP phones are SIP phones.

  • And not all VoIP phones are SIP phones.


SIP is pronounced like sip, but IP is pronounced like eye-pee.

Although SIP phones use IP (and are a type of IP phone), the "I" in SIP stands for "initiation" and the "I" in IP stands for "internet." The "S" stands for "session" and the "P" stands for "protocol."


Most telecom and data professionals pronounce VoIP as vee-oh-eye-pee, but amateurs say voyp.

Phones with HD (high definition) audio have extended frequency response for more lifelike sound -- but you should not expect anything special if the phone on the other end of the conversation is not an HD phone.


IP phones are not just for large corporations. They offer many advantages for small businesses, especially with employees working in multiple offices -- or at home.

Bits, bytes and gigs

  • Bit is the abbreviation for binary digit. Eights bits makes one byte, enough information to represent a letter or a number. A thousand bytes is a kilobyte (KB). A million bytes is a megabyte (MB). A billion bytes is a gigabyte (GB).

  • Bits are used for measuring speed (usually per second). Bytes are for size.

  • A bit is represented with a lowercase "b," and a byte is represented with an uppercase “B.” So Kb is kilobits, and KB is kilobytes. A kilobyte is eight times as large as a kilobit.

Here’s a comparison of file sizes: 

  • Short email: about 2KB

  • One-page letter: about 30KB

  • 10 megapixel color photo (JPG, compressed): about 6MB

  • 10 megapixel color photo (TIF, uncompressed): about 31MB

  • Words and pictures in one of my books: about 6MB

  • 3-min. song, compressed: about 4MB

  • 87-min. The Simpsons movie, compressed: 1.64GB

  • 30-min. video, compressed: about 500MB.

  • 57-sec. high-def Harry Potter trailer, compressed: 169MB

  • 90-min. high-def movie, compressed: 15 – 50GB


Here’s a comparison of approximate download speeds: 

  • Dial-up modem: 28Kb per second

  • T1: 1.544Mb per second

  • ADSL: 6Mb per second

  • Cable: 10Mb per second (or higher)

  • FiOS: 15-150Mb per second (download is faster than upload)

Here’s a comparison of approximate network speeds:

  • 10Base-T ethernet: 10 Mb per second

  • 100Base-T fast ethernet: 100 Mb per second

  • Gigabit ethernet: 1020 Mb per second

Some IP phones are marketed as "Gigabit Phones." They won't let you talk faster, but data moves faster so conversations can probably start sooner. They may also transmit and receive video.