Not all that popular. Most people only have three.
No.
smart phones
Yes, telegrams were popular before telephones became widespread. They provided a means of sending written messages over long distances quickly when phone lines were not available or practical.
Most companies have switched over to a completely cell phone based market. However the popular telephones that most companies choose to use are often made by Avaya, Cisco, or Toshiba.
There are a number of makes of conference telephones. Two of the more popular makes include Polycom and Cisco. Both makes of phone can be purchased from Amazon.
Trains, televisions, automobiles, airplanes, telephones, electricity,
Telephones'
Wireless telephones sometimes have interference due to low batteries or the base units being kept too close together. Contrary to popular belief, WiFi works on a different frequency and does not interfere.
Telephones were invented in 1876. No major milestone in telephones happened in 2000.
Telephones can able to communicate with other telephones through Public Switched Telephone Network, which transmit voice signal over circuit switching technology.
Wireless telephones are also known as mobile telephones. Examples of wireless telephones are Apple iPhones, HTC phones and Samsung Galaxy tablet/phones.
Every single country on earth has telephones.