If I were to purchase 2 pairs of this walkie talkie, would the 4 units be able to communicate with each other?

http://www.amazon.co.uk/Motorola-XTR-Twin-Walkie-Talkie/dp/B000Q8BO42/ref=wl_it_dp_o?ie=UTF8%26amp;coliid=I1N3G1ON2TYB4Y%26amp;colid=LEHJD5BEBWV1



If i bought 2 pairs, could each single unit send and recieve signals to and from all other 3 units? or would the communication be limited to the pairs they were sold in?If I were to purchase 2 pairs of this walkie talkie, would the 4 units be able to communicate with each other?
just put them on the same channel

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