Automatic routing technique

• US 6,021,191 A
• Filed: 03/05/1997
• Issued: 02/01/2000
• Est. Priority Date: 03/05/1997
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Chen, Jiayu, Zerling, David, Fishman, Saul Daniel, Ash, Gerald Richard
• Primary Examiner(s): Wolinsky, Scott
• Assistant Examiner(s): TIEU, BENNY QUOC
• Application Number:
  US08/811,979
• Time in Patent Office: 1,063 Days
• Field of Search: 379/221, 379/219, 379/220, 379/229, 379/230, 379/222, 379/207
• US Class Current: 379/221.05
• CPC Class Codes: H04Q 2213/1307 Call setup
• CPC Class Codes: H04Q 2213/13141 Hunting for free outlet, circuit or channel
• CPC Class Codes: H04Q 2213/13164 Traffic (registration, measurement,...)
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13352 Self-routing networks, real-time routing
• CPC Class Codes: H04Q 2213/1338 Inter-exchange connection
• CPC Class Codes: H04Q 2213/13383 Hierarchy of switches, main and subexchange, e.g. satellite exchange
• CPC Class Codes: H04Q 3/66 Traffic distributors

Abstract

The routing of calls from one network (100) to another network (170) may be accomplished by tracking the call completion history over each trunk group (174₁ -174₂) connecting the networks. From a knowledge of the call completion history for each route, a Completion Rate Factor (CRF), representing the ratio of completed calls to all calls attempted is computed. The route having the CRF representing the highest number of completions is then selected. Typically, the process is dynamic, so that if the selected route no longer has the highest number of completions, then the route previously found to have the highest number of call completions is selected. The concept of completion rate factor routing can be extended to multiple carriers to yield a carrier completion rate feature routing technique. Routing may also be completed in accordance with network congestion to route advance a call.

Claims

1. A method for routing calls between a first and second networks, comprising the steps of:

(a) routing calls between the first and second networks across a plurality of routes, each formed by at least one trunk group;

(b) recording, for each call across each route, a completion history indicative of whether said call was completed over an egress trunk within an egress trunk group to a far end following trunk seizure;

(c) establishing a Completion Rate Factor (CRF) for each route in accordance with the call completion history;

(d) establishing a load state for each route based on idle link bandwidth and reservation and traffic level on that route;

(e) selecting, among the routes over which future calls may be routed, the route having a CRF representing greatest call completions and lightest load state; and

(f) routing future calls on the selected route.

2. The method according to claim 1 wherein the completion history is determined based on whether a failure signaling message is received from the far end following seizure of the egress trunk.

3. The method according to claim 1 wherein the steps of (b), (c), (d), (e), and (f) are performed repeatedly in succession.

4. The method according to claim 1 wherein the step of selecting a route comprises the step of selecting the route having a lightly loaded egress trunk group.

5. The method according to claim 1 wherein the selecting step comprises the step of selecting the route having no non-completions within a prescribed interval.

6. The method according to claim 3 wherein the prescribed interval comprises 300 seconds.

7. The method according to claim 5 wherein if each route has at least one non-completion within the prescribed interval, then calls are routed on the path having the highest number of call completions and such call completions exceed a prescribed high call completion threshold.

8. The method according to claim 7 wherein if each route has at least one non-completion within the prescribed interval, and the highest number of call completions does not exceed the prescribed high call threshold, then calls are routed on the path whose average number of call completions exceeds a prescribed average call completion threshold.

9. The method according to claim 8 wherein if each route has at least one non-completion within the prescribed interval, the highest number of call completions does not exceed the prescribed high call threshold, and the highest number of call completions does not exceed the average number of call completions, then calls are routed on a path whose call completions exceeds a prescribed low call completion threshold.

10. The method according to claim 5 wherein the steps are performed repeatedly for the routes with a heavily loaded state egress trunk groups.

11. The method according to claim 5 wherein the steps are performed repeatedly for the routes with reserved state egress trunk groups.

12. A method for routing calls between first and second networks via multiple carriers, each capable of utilizing an overflow path for alternate transit, the method comprising the steps of:

(a) routing calls between the first and second networks via each of the carriers;

(b) recording, for each call carrier, a completion history of calls carried by said carrier indicative of whether the call was completed without alternate transit;

(c) establishing for each carrier a Non-Transit Rate Factor (NTRF) in accordance with the call completions not requiring alternate transit;

(d) selecting the carrier having a NTRF representing the highest number of call-completions not requiring alternate transit; and

(e) routing future calls over the selected route.

13. The method according to claim 12 wherein steps (b)-(e) are repeated continuously.