US 6,768,904 · Granted 2004-07-27

The Patent That Let You Switch From Voice Calls to Data Without Hanging Up

Back in the early 2000s, when mobile phones were still mostly for calling, this patent describes a clever trick: you're on a voice call with someone, and instead of hanging up and dialing again, you can flip into data mode (to send a fax or other data) while keeping that same connection alive. It's like switching lanes on a highway without leaving the road.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a method for converting an active voice communication channel into a data communication channel on a mobile terminal without disconnecting the existing voice call. Specifically, what's protected is the process of sending a connection request and the receiving terminal's telephone number to the mobile terminal (via an ATD command) so that the system can transition from Voice mode to Data mode while preserving the underlying connection. If someone implemented a system that allowed seamless mode-switching over the same active channel in this exact way, they would be infringing.

Why it matters

In the early 2000s mobile landscape, this represented a meaningful efficiency gain. Most phones at that time required you to terminate a voice call completely, then initiate a new data session. This patent's approach eliminated that friction by reusing the existing connection, making it faster and more practical for users who needed to send faxes or data while already on a call. For carriers and phone makers, it meant a better user experience without requiring separate infrastructure.

Real-world use

When you're talking to a colleague on your mobile phone and need to fax them a document, instead of saying goodbye, hanging up, redialing, and starting a fax transmission, you could stay connected and transition directly into fax mode on the same line.

Original USPTO abstract

A method for transmitting data in a data communication system having a mobile terminal and a transmitting/receiving terminal is enclosed. The method includes the steps of establishing a voice communication channel between the mobile terminal and a receiving data terminal in the data communication system set to a Voice mode, setting the data communication system to a Data mode without disconnecting the voice communication channel by transmitting a first connection request and a telephone number of the receiving data terminal by the transmitting data terminal to the mobile terminal, establishing a data communication channel between the transmitting and receiving data terminals, and transmitting data to the receiving data terminal through the data communication channel. By sending a receiving side telephone number to the mobile terminal together with a connection request signal (ATD command) as shown in the data communication method according to the present invention, a user can transmit or receive data more conveniently during the wireless conversation. The mode of the communication system can simply be converted from a Voice mode to a Data (Fax) mode by transmitting a ATD command together with a receiving side telephone number so that it can provide a substantial convenience to a user when transmitting or receiving data during the wireless phone conversation.

Patent details

Publication number: US 6,768,904
Filing date: 2001-10-02
Grant date: 2004-07-27
Assignee: Lg Electronics Inc.
Inventor(s): KIM SHIN
CPC class: H04N1/00307

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