Method and system for combining an emergency standalone switching device with a switching system interface

1. An emergency switching system with a switching system interface used to bypass a common control and switch matrix of a digital switch, the emergency switching system comprising:

a switching system interface used to bypass a common control and switch matrix of a digital switch;

an emergency standalone switch for controlling call control functions, the emergency standalone switch coupled to the switching system interface; and

means for routing a call from a first subscriber line to a second subscriber line through the emergency standalone switch;

whereby the emergency switching system provides emergency or local call service to a localized area serviced by the digital switch.

2. The emergency switching system of claim 1 wherein the digital switch is a class 5 digital switch.

3. The emergency switching system of claim 1 wherein the means for routing a call from a first subscriber line to a second subscriber line is a timeslot interchange device routing Pulse Code Modulation (PCM) data, the timeslot interchange device routing PCM data between a receive PCM bus and a transmit PCM bus on a timeslot.

4. The emergency switching system of claim 1 further comprising a database storing a plurality of directory numbers of subscribers located within the localized area, the database providing directory numbers for call control by the emergency standalone switch for providing local or emergency call service to a subscriber serviced by the digital switch.

5. The emergency switching system of claim 4 further comprising a digit collector for collecting numbers dialed by a subscriber, the digit collector using timeslots from the transmit PCM during call setup to capture dialed numbers from a subscriber, the digit collector providing the captured numbers to the emergency standalone switch for determining the desired number of the subscriber for local or emergency call service.

6. An emergency switching system with a switching system interface used to bypass a common control and switch matrix of a digital switch, the emergency switching system comprising:

a switching system interface used to bypass a common control and switch matrix of a digital switch;

means for routing Pulse Code Modulation (PCM) data; and

means for controlling call control functions autonomous from the digital switch through the means for routing data, wherein the means for controlling call control functions is coupled to the switching system interface, thereby providing limited call service to a plurality of subscribers.

7. The emergency system of claim 6 wherein the digital switch is a class 5 digital switch.

8. The emergency switching system of claim 6 wherein the means for routing PCM data includes routing PCM data between a receive PCM bus and a transmit PCM bus on a plurality of timeslots.

9. The emergency system of claim 8 wherein: the means for routing PCM data is a timeslot interchange device; and

the means for controlling call control functions is an emergency standalone switch for controlling call control functions through the timeslot interchange device.

10. The emergency system of claim 6 wherein the limited call service includes emergency or local subscriber service within an area normally serviced by the digital switch.

11. A method of providing call service for subscribers using a switching system interface used to bypass a common control and switch matrix of a digital class 5 switch, the method comprising the steps of:

utilizing a switching system interface to bypass a common control and switch matrix of the digital class 5 switch;

routing data between subscribers in a specified area;

controlling call control functions autonomous from the digital class 5 switch; and

providing local or emergency call service to a plurality of subscribers.

12. The method of providing call service of claim 11 wherein:

the step of routing data between subscribers includes routing Pulse Code Modulation (PCM) data between a received PCM bus and a transmit PCM bus.

13. The method of providing call service of claim 11 further comprising the steps of:

storing directory numbers associated with the plurality of subscriber;

dialing a directory number by at least one subscriber;

recognizing the dialed directory number as a stored directory number; and

connecting the call by the subscriber.

14. The method of providing call service of claim 13 wherein the step of recognizing the dialed stored directory number includes:

receiving the dialed directory number; and

matching the dialed directory number with a stored directory number.

15. The method of providing call service of claim 13 wherein the step of recognizing the stored number includes:

capturing dialed numbers transmitted by a subscriber;

identifying the dialed number; and

associating the dialed number with at least one stored directory number.

16. An emergency switching system with a switching system interface used to bypass a common control and switch matrix of a class 5 digital switching system, the emergency switching system comprising:

at least one network interface for terminating a digital transmission facility that is part of a network architecture;

at least one line/trunk interface, compatible with the internal signals used to operate the line/trunk interface of the class 5 digital switching system;

a switching means, connected to the network interface and to the line/trunk interface, for routing data between the network interfaces and the line/trunk interface;

a device for routing data, the device routing a call from a first subscriber line to a second subscriber line by routing data when access to the class 5 digital switching system is disconnected; and

an emergency standalone switch for controlling call control functions through the device in place of the switching means;

whereby the emergency switching system provides emergency or local call service to a localized area serviced by the class 5 digital switch.

17. The emergency switching system with a switching system interface of claim 16 wherein the device is a timeslot interchange device for routing Pulse Code Modulation (PCM) data between a receive PCM bus to any timeslot on a transmit PCM bus.

18. A method of providing call service for subscribers serviced by a digital class 5 switch, the method comprising the steps of:

accessing a connection providing internal signals used to control line and trunk interfaces of a digital switching system and convey data in and out of the line and trunk interfaces; and

applying a switching system interface, which is compatible with the connection providing internal signals, to the connection, the switching system interface bypassing at least a portion of the common control and switch matrix and being compatible with a digital transmission facility within the telecommunications network;

detecting a loss of access to the digital class 5 switch;

routing data between subscriber lines;

controlling call control functions by routing data between subscriber lines; and

providing local or emergency call service to a plurality of subscribers serviced by the digital class 5 switch.

19. The method of providing call service for subscribers of claim 18 wherein the step of routing data between subscriber lines includes routing Pulse Code Modulation (PCM) data between a receive POM bus and a transmit bus.

20. A switching system interface for bypassing the common control and switch matrix of a class 5 digital switching system for telecommunications networks, comprising:

a network interface for terminating a digital transmission facility within a network;

means for connecting the network interface to at least one line/trunk interface of a digital switching system, the means for connecting the network interface to the line/trunk interface being compatible with a signaling protocol for communicating with the line/trunk interface;

means for detecting a loss of control by a call control function of the network interface;

means for routing data between a first subscriber line and a second subscriber line when the call control function of the network interface is lost; and

means for controlling call control functions autonomously from the network interface through the means for routing data, thereby providing limited call service to a plurality of subscribers normally serviced by the network interface.

21. The switching system interface of claim 20 wherein the means for routing data is a timeslot interchange device routing Pulse Code Modulation (PCM) between a receive PCM bus and a transmit PCM bus on a timeslot.