 The same day, Bell's lawyer filed (hand-delivered to the U.S. Patent Office) a patent application on the harmonic telegraph, including its use for transmitting vocal sounds.On February 19, the patent office suspended Bell's application for three months to give Gray time to submit a full patent application with claims, after which the patent office would begin interference proceedings to determine whether Bell or Gray were first to invent the claimed subject matter of the telephone.At that time, the USPTO required the submission of a working patent model for the patent application to be accepted, with the acceptance process often taking years, and with interference proceedings that often involved public hearings—although the U.S. Congress had abolished the requirement for patent models in 1870.