With such a lot of information on the internet about two way radio's it is hard to discover the top and most candid information. heres a piece from a reputable website that i believe as accurate, don't quote me on it but please read and enjoy
As with so many emerging technologies, it was warfare that helped propel walkie-talkies from prototype to mass adoption in a short time. During World War II, the U.S. and Allied forces were the first to put these newfangled radios into widespread use.
There were several groups working on this type of radio in the late 1930s, so it's impossible to attribute the exact genesis of the walkie-talkie to one person or company. Radio engineer Al Gross and Canadian inventor Donald Hings were on the forefront of this technological wave, as were research groups at Gavin Manufacturing Company, which is now better known as Motorola.
Just before 1940, Motorola produced a portable AM transceiver that became known as a handie talkie. This was an AM-based system (on frequencies from 3 to 6 MHz). It worked, but it was prone to degrading signal quality, meaning static and interference often made communication frustrating.
The first design to hit the battlefield in mass numbers, and the first to garner the walkie-talkie label, was the Motorola SCR-300. The SCR-300 was also an FM-based device (40 to 48 MHz), and much more resistant to interference than AM. It also had better range, at around 3 to 5 miles (4.8 to 8 kilometers).
FM-based radio signals offered the advantage of squelch, which just meant that the speaker went silent until an incoming signal arrived. Prior to squelch capabilities, radio operators who monitored AM signals had to endure long periods of mind- and ear-numbing static when no one was transmitting on the channel that they were monitoring.
The SCR-300 wasn't exactly as convenient as your average pocket-sized smartphone. It required a backpack that housed the battery, electronics and a 33-inch (84-centimeter) antenna, all of which totaled more than 30 pounds (13.6 kilograms). Try dodging Nazi bullets and bombs with that load on your back.
In spite of its heft, the unit was rugged and reliable in war zones, and tens of thousands of them were deployed to troops in both the Pacific and European theaters. The end result was forces that could communicate and coordinate their activities much more effectively than ever before.
After WWII, walkie-talkie technology hit the mainstream. Military versions got smaller, lighter and more powerful. Amateur radio lovers adopted walkie-talkies en masse. Consumer-grade versions appeared, too, with affordable price tags that made them perfect for basic communications around the house, in the field, and even as toys.
No matter what purpose you use them for, walkie-talkies all work pretty much the same