It's important to order the right kind of cords for your phones.
Most "desk" phones have handset jacks on their sides.
But some phones have handset jacks on the bottom and cord retention channels (grooves) to hold the cords in place.
Standard handset cords can be difficult to install in these phones because you have to untwist them and stretch them out.
We have special handset cords with four-inch straight sections that are easy to install in the channels, so life will be easier if you order the right cords. Most companies don't sell these cords, but we do.
If you have a wall phone with a jack on the lower edge -- which you might logically call the bottom -- for purposes of selecting the cord, consider the jack to be on the side, not on the bottom, and order a standard cord.
Despite their male-sounding name, in the electronics business, jacks are considered to be "female" connectors. No one seems to know how this strange tradition started. Plugs are considered to be "male."
If you don't understand phone hardware gender, find someone of the opposite sex, get naked, and look in the mirror. Or you could study Michelangelo's "Temptation and Fall" on the Sistine Chapel ceiling in Rome.
Some folks talk about "jacking in," instead of "plugging in." That's silly. Lots of electricians call (female) electrical outlets, "plugs." That's silly, too.