Canadian Agricultural Products. To check for restrictions on fruits and vegetables from Canada, you can search the FAVIR database at www.aphis.usda.gov/favir/. Click the âFresh Fruit and Vegetablesâ link to the right to learn how to use the database.
The standard voltage for the telephone system is 48 volts DC. Ringing voltage is much higher, around 90 volts AC at a low frequency. When you place a load of about 600 ohms on the line, you are off hook or connected. Telephone ringer voltage is 50.5 volts at standing and -50.5 volts at ringing.
The first telephone was invented 1870 by Alexander Graham Bell. There was many others that looked into the invention of the telephone. The telephone switchboard was invented in 1876, which allowed for the formation of telephone exchanges, and eventually networks. http://en.wikipedia.org/wiki/Telephone.