In the United States, the symbol is usually called the pound sign and the key bearing this symbol on touch-tone phones is called the pound key. In Canada, this key is most frequently called the number sign key. In most other English-speaking countries the symbol is usually called the hash, and the corresponding telephone key is the hash key. Beginning in the 1960s, telephone engineers have attempted to coin a special name for this symbol, with variant spellings including octothorp, octothorpe, octathorp, octotherp, octathorpe, and octatherp;[2] none has become widely accepted.