Method and apparatus for accessing a network computer to establish a push-to-talk session

This application is a continuation-in-part of U.S. Ser. No. 10/302,882 filed Nov. 25, 2002, pending, entitled “Method And Apparatus For Correlating A Unique Identifier, Such As A PSTN Telephone Number, To An Internet Address To Enable Communications Over The Internet,” which is a continuation of U.S. Ser. No. 09/456,646, filed Dec. 8, 1999, now U.S. Pat. No. 6,539,077, which is a continuation-in-part of U.S. Ser. No. 09/226,901 filed Jan. 8, 1999, now abandoned, and a continuation-in-part of U.S. Ser. No. 09/092,764 filed Jun. 5, 1998, now U.S. Pat. No. 6,292,799, to which priority is claimed and which are hereby incorporated by reference in their entirety.

This invention relates to communications services, and in particular to the extension of a wireless push-to-talk (PTT) service to include communication with any number of network computers, not registered for PTT service, but accessible by a public data network like the Internet.

Push-to-talk (PTT) service over cellular or wireless networks provides a type of half-duplex or one-way communications service between two or more users. See e.g., the Push-to-talk over Cellular (PoC) architecture, of the Open Mobile Alliance Ltd. Users often form a group, a predefined set of users, who then communicate with each other in a “point-to-multipoint” fashion. The communications are one-way: while one person (user) speaks, the other(s) listen(s). Turns to speak are generally granted on a first come, first serve basis by a user pressing a push-to-talk key or button on his/her wireless phone (or other user equipment). However, the PTT service provider may apply some type of arbitration process in order to insure “fair” access among the members of a PTT session.

Push-to-talk functionality is typically delivered across a mobile operator\'s private Internet Protocol (IP) data network using standard VoIP (Voice over IP) protocols, although other technology implementations are possible. In a typical IP network scenario, a mobile phone user with a push-to-talk enabled phone enters a PTT address for another mobile user who is registered for push-to-talk services and then presses the push-to-talk key on his/her mobile phone to initiate a session. In a typical scenario, the address of the destination mobile user can be based either on a mobile phone number (e.g., 1-978-555-1212) or on an Internet address in the form of a network access identifier (e.g., user@operator.com). If the destination user is available, the originator receives an immediate indication that the destination user is available and the originator can begin speaking. The call originator\'s voice is sent through the wireless operator\'s private IP network to the target handset. The call connection over the operator\'s IP network is almost instantaneous. Initiating a push-to-talk session to a mobile/wireless user who is not available simply results in a negative response tone.

FIG. 1 illustrates an example of a wireless operator\'s push-to-talk service (PTT service) as described in U.S. Pat. No. 6,360,093 to Ross. A wireless phone (102) with a push-to-talk button (104) registers with a push-to-talk server (PTT server) (110) located on the wireless operator\'s IP network (108), using standard VoIP protocols. A base station (106) provides the interface between the radio signals used to communicate with the wireless phone and the service provider\'s IP network. The PTT server (110) maintains a database of registered wireless phones (102, 103, 105) and associated Internet addresses. The PTT server acts as the clearance or acceptance point for all push-to-talk sessions with its registered wireless users. All push-to-talk session requests are first presented to the PTT server which then forwards or proxies the request (via base stations 106, 107) to the appropriate registered destination wireless phone(s). A network computer (112) with PTT functionality (109) may also be configured to emulate a combined base station and wireless phone and register for push-to-talk services with the wireless operator\'s PTT server.

A PTT server can establish a push-to-talk session between two or more of its locally registered wireless phones or network computers. The PTT server(s) of one PTT service provider can also be configured to communicate with a known set of PTT servers of one or more other PTT service providers to enable push-to-talk sessions between two or more wireless phones or computers, each of which is registered with a different PTT service provider. What it cannot do, however, is establish a push-to-talk session with a push-to-talk enabled computer that is not registered with any operator\'s PTT service.

Systems and methods consistent with implementations of the present invention are provided in which a PTT service can access a Directory Service (DS), via a public data network such as the Internet. The DS contains push-to-talk addresses and associated unique identifiers for any number of network computers, accessible via the Internet, that can support push-to-talk functionality but are not registered with any PTT service. A network computer with push-to-talk functionality has its push-to-talk address recorded with the Directory Service and is assigned a unique identifier by the Directory Service.

According to one method, a wireless phone user registered for push-to-talk services with a wireless operator\'s PTT server initiates a push-to-talk session with an unregistered network computer by entering the network computer\'s unique identifier as a destination address for a push-to-talk session. The PTT server uses the unique identifier provided by the originating wireless phone user, to query the Directory Service to obtain a push-to-talk address for the destination computer and then forwards or proxies the push-to-talk request to the destination computer. As a result, the number of push-to-talk destinations available to the wireless phone user is expanded to include any number of push-to-talk enabled network computers that are known to the Directory Service. In the event that the user of the destination computer is not available to accept a push-to-talk session, the push-to-talk software running on the destination computer can be optionally configured to return a signal indicating that the caller can begin speaking a message that the computer will record in the form of a push-to-talk message, similar to a voice message, that the called party can review at a later time.

More generally, according to one implementation, a wireless phone, having PTT functionality and registered with a PTT server, sends a request for a PTT session to the PTT server. The request includes a unique identifier of a destination network computer, accessible on a public data network, having PTT functionality and not registered with a PTT server. The PTT server receives the request and sends a query for a PTT address for the destination network computer to a Directory Service accessible on the public data network. The Directory Service receives the query and returns the PTT address to the PTT server. The PTT server receives the PTT address and sends a request for a PTT session to the destination network computer.

In various method embodiments, the public data network is the Internet. The PTT address may be a Session Initiation Protocol (SIP) address, which for example may be a SIP uniform resource identifier (SIP-URI) that can be resolved into an IP address and a port number for receiving PTT sessions at the network computer. As used herein, the network computer may be any of various devices accessible via a public data network, via a fixed line and/or wireless connection, which include a processor and memory and PTT functionality. For example, the network computer may be a personal computer or a hand-held device such as a Personal Digital Assistant.

In various embodiments, the unique identifier which enables PTT access to the network computer can be in the form of a fixed or variable length name or number. In select embodiments, the name or number is prefixed with a * or a # character. In a particular embodiment, the unique identifier is a telephone number in the form of an ITU-T recommended E.164 format, with a # prefix.

In an apparatus embodiment, a PTT server contains means for querying a Directory Service, accessible on a public data network, with a unique identifier to obtain a PTT address for initiating a PTT session with a destination network computer not registered with a PTT server. The means for querying may be any combination of hardware and/or software. The means for querying include means for sending a request for and in response receiving the PTT address from the Directory Service. The server also includes means for sending a PTT session request to the destination network computer and means for receiving a PTT response from the network computer. The server also includes means for accessing a user equipment registered with the PTT server, such as a wireless phone or network computer. The server includes means for receiving a request for a PTT session from the registered user equipment with the unique identifier, and means for sending the user equipment a session response.

In another embodiment, an apparatus is provided which includes a Directory Service, residing on a computer and accessible on a public data network, which contains at least one unique identifier and an associated PTT address of a network computer having PTT functionality (and which computer is) accessible on the public data network. The Directory Service may store the PTT address and associated unique identifier as one or more domain name system (DNS) resource records. The resource records may be in the format of Naming Authority Pointer (NAPTR), Service (SRV) and A (IP-address) records.

A method is also provided of establishing a push-to-talk session between an inviting user (originator) and an invited user (destination), the improvement comprising that when the invited user is not available to accept a push-to-talk session, the user equipment of the invited user signals the inviting user to record a push-to-talk message.

These and other embodiments are described in greater detail in the accompanying figures and following detailed description.