Casio G'zOne Commando

i work for an indirect agent and we have just recently had customers tell us that there is no way to do a backslash on this phone. you can do a forward slash but no backslash. i investigated this and i have not figured it out yet. so if anyone knows how to do this or a way around it please let us know? and i assume that by downloading an differant keyboard from the marketplace would remedy this situation but we do not have an active commando to try that on.