ENUM Server Caching for VoIP Call Completion
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Solution Overview
Problem
VoIP networks face call setup failures due to network element failures in the IP backbone network, leading to degraded reliability, as existing solutions fail to ensure seamless call completion in the event of DNS server unavailability.
Innovation Solution
Implementing an ENUM server with a stored address updating procedure that maintains NAPTR records with numeric IP addresses, allowing call setup to continue even if the DNS server is unavailable by using previously stored IP addresses, ensuring call completion through the ENUM server's cached information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system relies on DNS servers for address resolution in VoIP networks, then address mapping functionality is provided, but call setup failures occur when DNS servers are unavailable
Solution Approach 1:
The ENUM server pre-resolves and stores address mappings (NAPTR records) in its database before they are needed. When a call needs to be set up, the system queries the pre-computed ENUM records rather than performing real-time DNS resolution, ensuring call setup can proceed even if DNS servers are unavailable.
Solution Approach 2:
The ENUM server acts as an intermediary between the VoIP network and the DNS system. It caches address mapping information from DNS queries and provides this cached information to calling systems, decoupling the call setup process from direct DNS server dependency and improving reliability.
2Loss of time
If real-time DNS queries are performed for each call setup, then current IP addresses are obtained, but call setup time increases and failures occur during DNS unavailability
Solution Approach 1:
Address mappings are resolved and stored in the ENUM server database in advance. When a call needs to be established, the system retrieves pre-computed NAPTR records from the ENUM server rather than performing time-consuming real-time DNS queries, significantly reducing call setup time.
Solution Approach 2:
The ENUM server creates and maintains copies of address mapping information from the DNS system in its own database. These cached copies can be quickly retrieved without requiring real-time access to DNS servers, reducing both time and reliability concerns.
3Reliability
If the system uses traditional PSTN-style call routing, then call completion is reliable, but migration to VoIP networks results in call setup failures due to network element failures
Solution Approach 1:
The ENUM server serves as an intermediary that adapts VoIP network address resolution to work more reliably like traditional PSTN routing. By caching address mappings and providing them through a dedicated ENUM query interface, it isolates VoIP call setup from the volatility of the IP backbone network while maintaining VoIP network compatibility.
Solution Approach 2:
The system prepares address mapping information in advance and stores it in the ENUM server database, creating a buffer or cushion against potential DNS server failures or IP backbone network issues. This pre-computed information ensures that call setup can proceed even when network conditions are unfavorable.
Data Source
AI summary
Methods and apparatus to enable call completion in Internet protocol communication networks are disclosed. Example methods disclosed herein to process a voice over Internet protocol call include sending a first query to a telephone number mapping server to obtain a session initiation protocol uniform resource identifier associated with a destination device with which the voice over Internet protocol call is to be established. Some such example methods further include, in response to the voice over Internet protocol call failing to be established using the session initiation protocol uniform resource identifier obtained from the first query, sending a second query to the telephone number mapping server to obtain a numeric Internet protocol address associated with the destination device, and using the numeric Internet protocol address obtained from the second query to establish the voice over Internet protocol call with the destination device.