A programmable telecommunications switch has automatic backup of line cards to provide complete redundancy. The switch has I/O cards which terminate the external telecommunications spans. Each I/O card passes the data from its spans to a line card. When the line card fails, the I/O card switches the data onto an I/O bus which is connected to a standby I/O card. The standby I/O card switches a standby line card into connection with the I/O bus such that the data stream is then serviced by the standby line card. The failed line card may then be removed and replaced. All I/O cards are attached to the I/O bus such that redundancy for all active line cards using the same signalling protocol is provided with a single standby line card. With multiple I/O busses, standby I/O cards and standby line cards, multiple redundancy is possible. Finally, the failure of a single line module of a line card may be handled by switching only the span serviced by that module to a standby line card. Spans from different I/O cards may be serviced by different line modules of a single standby line card, and may be all connected to the same standby line card by the same bus.

A method and system to connect an optical network unit with a plurality of user sites. The invention includes the steps of and circuitry for connecting a plurality of line circuits to a cross-connect matrix. The optical network unit contains both the line circuits and the cross-connect matrix. In the invention, a plurality of drop connectors connect the cross-connect matrix to a plurality of user sites such as homes. The method and system further include circuitry that remotely controls the cross-connect matrix from a central office or network management system to connect selected ones of the line connectors to selected ones of the drop connectors and, thereby, electrically connect the optical network unit to the plurality of user sites.

Redundant facility payload signals (12, 14) received by redundant interface modules (16, 18) are redundantly provided (28, 30; 32, 34) to redundant downstream modules (24, 26) in an equipment (10). A non-symmetrical facility protection algorithm is resident in the B interface module (18). Symmetrical equipment protection algorithms are independently resident and operative in each module of pairs of identical A and B modules at each stage of the data stream. Module or data failures result in switchover only of the disabled data path or module so that the ability to transport payload is maintained and other modules or data paths are unaffected. Facility switchover is effected by detecting a working line failure and transmitting commands to switch the protection line to the A path modules. Equipment switchover is effected by checking for a working or protection module failure independently in each path and independently communicating independent switchover decisions to the other side and downstream. The methodology and mechanism are disclosed in a SONET element embodiment, although the invention is applicable in other contexts.

A telephone advertising service provides a short advertising message through a telephone receiver as a telephone call is initiated. The advertising message is stopped after a predetermined run time, and an invitation-to-dial tone is added. The advertising message is stopped when a subscriber starts to dial numbers. The method provides the advertising messages in lieu of invitation-to-dial tones. Differentiated subscribers are individually provided with distinct advertising messages. Subscribers are distinguished by characteristics of exchange number, monthly call volume, call type, geographical location and time of day. The advertising messages are provided by a message system rack connected to a digital or analog telephone exchange. Each rack has plural message recorders and plural cards connected to multiple users. Software controls a connection network. Subscriber lines are sampled to sense when a call is being initiated and to signal to a controller that a telephone call is being initiated. A PCM audio interface is activated. An available message channel is switched to the subscriber line, and a corresponding message is played over the subscriber line. Soon the subscriber line is connected to the telephone exchange, and an invitation-to-dial tone is provided. Several different messages are offered in different sets of channels, changing the messages depending on the time of day. When a prohibit service signal is active, the subscriber line is switched directly to the telephone exchange.

Asynchronous Transfer Mode (ATM) cells are conveyed over a shelf bus to and from an NT (network termination) card inserted into the bus connected to an ATM network and to a plurality of LT (line termination) cards also inserted into the bus, wherein the NT card processes the ATM cells and provides downstream cells to the bus with a guard byte and upstream cells to the ATM network without a guard byte.