Abstract: A cordless telephone system achieves synchronism for each one of multiple portable units to the same communication channel for communicating with a common base unit. The cordless system uses a dual channel process to allow both the freedom to dynamically change channels as needed to avoid interference while simultaneously providing a capability to resynchronize any portable unit with the base unit on a selected active channel. This is achieved through the use of a fixed service channel and an active channel which changes as needed. If a channel change is made during a call, after the call is completed, the base unit returns to the previous active channel and broadcasts a message to the multiple portable units indicative of the new active channel. Also, any portable unit that attempts to communicate with the base unit on the wrong channel and fails to get a response will transmit a message on the fixed service channel requesting the current active channel from the base unit.

Abstract: A cordless telephone arranged for operation in a frequency hopping system includes an arrangement which achieves optimum utilization of multiple cordless telephone portable units by permitting these units to access a common base unit and also access each other. The portable units are configured for subsequent operation with the base unit and each other during a registration process by having the base unit select from a plurality of communication channels available in the frequency hopping system a different starting channel for each one of the portable units. The portable units are thereby advantageously selectably addressable by the base unit and by each other. Any one of the registered portable units, for example, is capable of selectively paging and communicating with any other one of the registered portable units over selected ones of the plurality of communication channels.

Abstract: A cordless telephone arranged for operation in a frequency hopping system includes an arrangement which achieves optimum utilization of multiple cordless telephone portable units by permitting these units to access a common base unit and also access each other. The portable units are configured for subsequent operation with the base unit and each other during a registration process by having the base unit select from a plurality of communication channels available in the frequency hopping system a different starting channel for each one of the portable units. The portable units are thereby advantageously selectably addressable by the base unit and by each other. Any one of the registered portable units, for example, is capable of selectively paging and communicating with any other one of the registered portable units over selected ones of the plurality of communication channels.

Abstract: A cordless telephone system includes an arrangement wherein multiple portable units operate with a common base unit using the same security code without conflict or confusion. When a portable unit attempts to establish a radio link with the base unit, for example, this originating portable unit generates a random number which is retained by this unit and also transmitted to the base unit. This random number is substituted for the common stored security code, then shared by the base unit and all of the portable units, for creating a temporary unique security code that is known only to the base unit and the originating portable unit. Interference from other portable units attempting to gain access to the base unit while the originating portable unit is actively communicating with the base unit is thereby advantageously prevented.

Abstract: A cordless telephone arranged for operation in a frequency hopping system includes multiple portable units configured for operation with a base unit and with each other by having the base unit pseudo randomly select from a plurality of communication channels available in the frequency hopping system a different starting channel for each one of the portable units. Each portable unit then provides initial communications with the base unit over the selected starting channel of the portable unit. For maintaining communications during a frequency hopping cycle between a portable unit and the base unit, the portable unit and base unit both generate a set of communication channels from the starting channel assigned to the portable unit for subsequent use in communicating over the radio frequency link. Each of the portable units is configured for operation with the base unit and with each other during a registration procedure.

Abstract: A cordless telephone arranged for operation in a frequency hopping system conserves battery power in a handset unit when this unit is located remote from an associated base unit and in a standby state. While in this standby state, the handset unit resides in a low power monitoring mode and monitors a channel pseudo-randomly selected from a plurality of available channels in the frequency hopping band for receipt of an initialization signal from the associated base unit. The base unit similarly monitors this selected one of the channels for receipt of this initialization signal from the handset unit. Should ongoing communications between the base unit and the handset unit be inadvertently interrupted, the cordless telephone quickly re-establishes communications in the frequency hopping system through an initialization process executed by both the handset unit and the base unit.

Abstract: A cordless telephone arranged for operation in a frequency hopping system automatically modifies a frequency hopping sequence in the presence of interference detected on its in-use communication channels. Substitute alternative communication channels are identified and then substituted for those communication channels experiencing the interference without disruption of communications between a handset unit in the cordless telephone and its associated base unit.