Signaling protocol for multilink access network-local exchange interfaces

• US 5,822,420 A
• Filed: 08/30/1996
• Issued: 10/13/1998
• Est. Priority Date: 08/30/1996
• Status: Expired due to Fees

• Current Assignee: Digital Technics, L. P.
• Original Assignee: Digital Technics, Inc.
• Inventors: Davis, Steven, Loghmani, Masoud, Bolon, Brian
• Primary Examiner(s): Matar, Ahmad F.
• Assistant Examiner(s): Wolinsky, Scott
• Application Number:
  US08/706,220
• Time in Patent Office: 774 Days
• Field of Search: 379/196, 379/197, 379/198, 379/199, 379/200, 379/201, 379/207, 379/229, 379/230, 379/231, 379/333, 379/232, 379/234, 379/219, 379/220, 379/399, 370/329, 370/335, 370/336, 370/431, 370/432, 370/433, 370/434, 370/437, 370/441, 370/442, 370/464
• US Class Current: 379/230
• CPC Class Codes: H04Q 11/0421 Circuit arrangements therefor
• CPC Class Codes: H04Q 2213/13098 Mobile subscriber
• CPC Class Codes: H04Q 2213/13145 Rerouting upon failure
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13167 Redundant apparatus
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/13204 Protocols
• CPC Class Codes: H04Q 3/58 Arrangements providing connection between main exchange and sub-exchange or satellite

Abstract

A protocol for multilink access network-local exchange (AN-LE) interfaces is provided for common channel signaling on all AN-LE links and the transfer of calls and control to operational links upon detection of a link failure. The protocol permits the AN to assign channels on an AN-LE link and is error-tolerant and self-aligning.

Claims

1. A method of processing calls transmitted between a subscriber unit and an access network device and a network, the access network device being connected to the subscriber unit, and to the network via a network interface device and at least one communications link comprising a number of channels, the network interface device being an integral part of the network or independent of the network, comprising the steps of:

determining via said access network device whether one of said channels is available on said communications link for an outgoing call attempt initiated by said subscriber unit;

assigning said channel to said outgoing call attempt using said access network device;

notifying said subscriber unit that said channel is available and is to be used for said outgoing call attempt; and

notifying said network interface device that said outgoing call attempt will occur on said channel, said network interface device being programmed to process said outgoing call attempt using said channel assigned by said access network device without first assigning one of said channels and notifying said access network device of said channel selected by said network interface device.

2. A call processing method as claimed in claim 1, further comprising the step of reporting an off-hook condition at said subscriber unit to said access network device and then to said network interface device as an indication of said outgoing call attempt in lieu of sending a physical off-hook signal generated by said subscriber unit.

3. A call processing method as claimed in claim 1, further comprising the steps of:

determining whether said network interface device can accept said outgoing call attempt;

transmitting a response signal from said network interface device to said access network device indicating when said outgoing call attempt is not successfully received by said network interface device; and

releasing said channel.

4. A call processing method as claimed in claim 3, further comprising the step of transmitting a signal from said access network device to said subscriber unit to indicate that said outgoing call attempt has been rejected if said access network device has determined that at least one of a first condition and a second condition exists, said first condition corresponding to none of said channels being available between said access network device and said network interface device, said second condition corresponding to lack of a communication channel between said subscriber unit and said access network device for an outgoing call resulting from said outgoing call attempt.

5. A call processing method as claimed in claim 1, further comprising the steps of:

determining whether said network interface device can accept said outgoing call attempt; and

performing at least one of a plurality of functions comprising seizing a trunk using said network interface device to connect said subscriber unit to said network, and receiving dialed digits for routing a corresponding outgoing call resulting from said outgoing call attempt from said subscriber unit, if said outgoing call attempt can be processed by said network interface device.

6. A call processing method as claimed in claim 5, further comprising the steps of:

determining priority of of an outgoing call resulting from said outgoing call attempt at said network interface device using said dialed digits received from said subscriber unit; and

notifying said access network device to process said outgoing call attempt in accordance with a different priority.

7. A method of processing calls transmitted between a subscriber unit, an access network device connected to the subscriber unit, and a network interface device connected to the access network device via at least one communications link comprising a number of channels and to a network, comprising the steps of:

receiving an in coming signal at said network interface device from said network, said in coming signal corresponding to an incoming call;

transmitting a command signal from said network interface device to said access network device indicating that said incoming call is forthcoming;

determining via said access network device whether one of said channels is available;

assigning said channel to said incoming call using said access network device;

notifying said subscriber unit if said channel is available; and

transmitting an answer signal to said network interface device from said access network device.

8. A method of processing calls transmitted between a subscriber unit, an access network device connected to the subscriber unit, and a network interface device connected to the access network device via at least one communications link comprising a number of channels and to a network, comprising the steps of:

determining via said access network device whether one of said channels is available for a call;

detecting a condition to terminate said call at said access network device;

determining whether said network interface device should be notified of said condition; and

transmitting a command to terminate said call to said network interface device if said network interface device had been notified that one of said channels on said link had been assigned for said call by said access network device.

9. A method of processing a call between a first subscriber unit and a second subscriber unit, both of which are connected to an access network device, a network interface device being connected to the access network device via a communication link comprising a plurality of channels and to a network, comprising the steps of:

determining via said access network device whether a first channel is available from among said plurality of channels for a call initiated by said first subscriber unit;

assigning said first channel to said call using said access network device;

notifying said first subscriber unit that said first channel is available;

notifying said network interface device that said call is forthcoming and on which of said plurality of channels said call is being transmitted, said network interface device being programmable to process said call using said first channel assigned by said access network device without first assigning one of said plurality of channels and notifying said access network device of said channel selected and assigned by said network interface device;

processing said call on said first channel using said network interface device to determine where said call is to be routed;

transmitting a command signal from said network interface device to said access network device indicating that said call is being routed thereto;

determining via said access network device whether a second channel from among said plurality of channels is available for routing said call to said second subscriber unit;

assigning said second channel to said call using said access network device;

sending a response signal from said access network device to said network interface device to indicating whether said second channel has been assigned;

notifying said second subscriber unit if said channel is available, said second subscriber unit proceeding to go off-hook; and

transmitting an answer signal to said network interface device from said access network device to complete said call between said first subscriber unit and said second subscriber unit if said second channel has been successfully assigned by said access network device.

10. A method of processing calls transmitted between a subscriber unit and an access network device and a network, the access network device being connected to the subscriber unit, and to the network via a network interface device and at least one communications link comprising a number of channels, the network interface device being an integral part of the network or independent of the network, comprising the steps of:

receiving an incoming call indication signal at said network interface device from said network, said incoming call indication signal corresponding to an incoming call attempt for said subscriber unit;

transmitting a command signal from said network interface device to said access network device indicating that said incoming call attempt is forthcoming for said subscriber unit;

determining via said access network device whether one of said channels is available;

assigning said channel to said incoming call attempt using said access network device;

notifying said subscriber unit of said incoming call attempt and said channel to use for a corresponding incoming call resulting from said incoming call attempt; and

transmitting an answer signal to said network interface device from said access network device when said subscriber unit answers said incoming call.

11. A method of processing calls transmitted between a subscriber unit and an access network device and a network, the access network device being connected to the subscriber unit, and to the network via a network interface device and at least one communications link comprising a number of channels, the network interface device being an integral part of the network or independent of the network, comprising the steps of:

detecting a condition to terminate an established call at said access network device via a call termination indication signal from one of the subscriber unit and the network;

determining whether said network interface device should be notified of said condition if said call termination signal is from the subscriber unit;

transmitting a command to terminate said call to said network interface device from said access network device if said call termination indication signal is from the subscriber unit and if said network interface device had been notified that one of said channels on said link had been assigned for said call by said access network device; and

transmitting a command to terminate said call to said access network device from said network interface device if said call termination indication signal is from the network.

12. A method of processing a call between a first subscriber unit and a second subscriber unit, both of which are connected to an access network device, a network interface device being connected to the access network device via a communication link comprising a plurality of channels and to a network, comprising the steps of:

determining via said access network device whether a first channel is available from among said plurality of channels for an outgoing call attempt initiated by said first subscriber unit;

assigning said first channel to said outgoing call attempt using said access network device;

notifying said first subscriber unit that said first channel is available and is to be used for said outgoing call attempt;

notifying said network interface device that said outgoing call attempt will occur on said first channel, said network interface device being programmed to process said outgoing call attempt using said first channel assigned by said access network device without first assigning one of said plurality of channels and notifying said access network device of said channel selected and assigned by said network interface device;

processing an outgoing call corresponding to said outgoing call attempt on said first channel using said network interface device to determine where said call is to be routed;

transmitting a command signal from said network interface device to said access network device indicating that an incoming call attempt is forthcoming for said second subscriber unit;

determining via said access network device whether a second channel from among said plurality of channels is available for routing said call to said second subscriber unit;

assigning said second channel to said incoming call attempt using said access network device;

sending a response signal from said access network device to said network interface device to indicating whether said second channel has been assigned and which of said plurality of channels has been assigned to be said second channel;

notifying said second subscriber unit of said incoming call attempt and said second channel to use for an incoming call resulting from said incoming call attempt;

transmitting an answer signal to said network interface device from said access network device; and

completing said call between said first subscriber unit and said second subscriber unit via said network interface device.