1. A voice recognition server connected to a telephone equipment allowed to use a plurality of telephone numbers assigned to a single terminal and configured to convert a voice from the telephone equipment to character data, said voice recognition server comprising: voice receiving module which receives a voice from the telephone equipment; model storing module which stores at least one acoustic model and at least one language model used for converting the voice received by the voice receiving module, to character data; number deciding module which decides a current calling number being a currently calling telephone number of the telephone equipment, and a second number being a telephone number except for the current calling number out of the plurality of telephone numbers; model selecting module which selects an acoustic model stored in the model storing module, based on the current calling number and the second number, and which selects a language model stored in the model storing module, based on the current calling number; and voice recognition module which converts the voice received by the voice receiving module, to character data, based on the acoustic model and the language model selected by the model selecting module.