Method of enhancing call processing in a number portability environment

• US 6,233,331 B1
• Filed: 12/01/1999
• Issued: 05/15/2001
• Est. Priority Date: 05/22/1997
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Slutsman, Lev, Tewani, Kamlesh T., Wilson, Lance Wayne
• Primary Examiner(s): Matar, Ahmad
• Assistant Examiner(s): TIEU, BENNY QUOC
• Application Number:
  US09/458,660
• Time in Patent Office: 531 Days
• Field of Search: 379/219, 379/220, 379/221, 379/207, 379/229, 379/230, 379/242
• US Class Current: 379/220.01
• CPC Class Codes: H04Q 11/0435 Details
• CPC Class Codes: H04Q 2213/13097 Numbering, addressing
• CPC Class Codes: H04Q 2213/13102 Common translator
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/13216 Code signals, frame structure
• CPC Class Codes: H04Q 2213/13345 Intelligent networks, SCP
• CPC Class Codes: H04Q 3/005 Personal communication services, e.g. provisions for portability of subscriber numbers

Abstract

A method is provided which reduces post-dial delay in a number portability environment. In particular, a switching office which controls call routing to portable numbers (NPA-NXXs) contains a cache for which location routing number response information may be stored. The processing office concurrently checks the cache for LRN response information corresponding to the dialed number and launches a query to a number portability database. Thus, if the LRN response information in the cache is valid then the call will be routed in the timeliest manner. However, if either the cache does not have any LRN response information or the LRN response information in the cache proves not to be valid then, the switching office will have received the LRN response information from the database more quickly based on the concurrent launching of a query. Therefore, a more timely attempt at establishing a proper connection to the dialed number will occur thereby reducing post-dial delay.

Claims

1. A method for reducing post dial delay in a network providing a number portability environment, the method comprising the steps of:

receiving a dialed number;

recognizing said dialed number as a portable number;

checking a cache to determine if a location routing number for said portable number has been cached and whether the cached location routing number is reliable;

while said step of checking said cache is performed, if said cached location routing number is unreliable, querying a database that correlates portable numbers to respective location routing numbers to determine a location routing number for said portable number from said database;

if said step of checking determines a location routing number for said portable number has been cached and is reliable, then attempting to route the call to said portable number using location routing number response information from said cache; and

if said step of checking determines an unreliable location routing number for said portable number in said cache;

receiving location routing number response information corresponding to said portable number from said database in response to the step of querying, and

attempting to route the call to said portable number using said location routing number response information received from said database.

2. The method of claim 1, wherein said cached location routing number is reliable if it is cached less than a specified period of time.

3. The method of claim 1, wherein said cached location routing number is unreliable if it is cached longer than a specified period of time.

4. The method of claim 3 further comprising the step of:

updating said unreliable cached location routing number with said location routing number response information received from said database.

5. The method of claim 4 further comprising the step of:

receiving a notification of failure to complete the call to said portable number after attempting to route the call using said location routing number response information from said cache.

6. The method of claim 4 further comprising the step of:

starting a timer once said unreliable cached location routing number is updated with said location routing number response information received from said database, wherein said timer counts up to the specified period of time.

7. The method of claim 6 further comprising the step of:

flushing said cached location routing number from said cache once the specified period of time being counted by the timer has been reached.

8. The method of claim 6 further comprising the step of:

resetting the timer upon a successful cache hit for said location routing number in said cache.

14. The method of claim 6 further comprising the step of:

flushing said cached location routing number from said cache once the specified period of time being counted by the timer has been reached.

15. The method of claim 14 further comprising the step of:

resetting the timer upon a successful cache hit for said location routing number in said cache.

9. In a communication system in which a telephone number is portable between at least two service providers, a method for reducing post-dial delay for an originating party calling the portable number, the method comprising the steps of:

receiving a dialed number;

checking a cache for a cached location routing number associated with said dialed number and determining whether said cached location routing number associated with said dialed number is unreliable;

if said cached location routing number is determined to be unreliable;

launching a query to a database for obtaining a location routing number for said dialed number from said database, wherein said query is launched concurrent with said step of checking said cache;

receiving location routing number response information from said database in response to said query; and

if said step of checking determines that said cached location routing number is reliable, then, prior to receiving a response from said database, attempting to route the call to said portable number using said cached location routing number from said cache.

10. The method of claim 9, wherein said cached location routing number is reliable if it is cached less than a specified period of time.

11. The method of claim 9, wherein said cached location routing number is unreliable if it is cached longer than a specified period of time.

12. The method of claim 11 further comprising the step of:

updating said cached location routing number that is determined to be unreliable with said location routing number response information received from said database.

13. The method of claim 12 further comprising the step of:

starting a timer once said cached location routing number determined to be unrelaible is updated with said location routing number response information received from said database, wherein said timer counts up to the specified period of time.