IGAR System for Alternate SIP Call Routing
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Solution Overview
Problem
Existing SIP network systems fail to effectively route calls when the primary wide area network is overloaded, leading to unsatisfactory quality of service and bandwidth issues, and existing solutions are either slow or require manual intervention or are limited to peer-to-peer systems.
Innovation Solution
The implementation of an inter-gateway alternate routing (IGAR) system that uses the PSTN for call routing between SIP endpoints, allowing for automatic selection of terminal gateways based on cost indices and unique identifiers, enabling faster and cheaper call establishment without requiring tight control by a communications server.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual dial-out on public network trunk is used when private switching facilities fail, then users can reach destination parties, but the process requires manual intervention and is slow
Solution Approach 1:
The system performs preliminary actions by automatically detecting network failures and initiating alternate routing procedures without waiting for user intervention. The call controller monitors network status and proactively switches to PSTN fallback when IP network quality degrades, eliminating the time loss associated with manual detection and dialing.
Solution Approach 2:
The system implements self-service by enabling automatic failure detection and self-healing through autonomous routing decisions. The call controller continuously monitors network conditions and automatically initiates PSTN fallback when thresholds are exceeded, eliminating the need for user intervention and reducing call establishment time.
2Reliability
If PSTN Fallback is implemented to force calls to PSTN when IP trunk connection experiences unacceptable QoS, then call quality is maintained, but the system requires complex monitoring and automatic port management
Solution Approach 1:
The system uses parameter changes by monitoring specific network quality metrics (delay and packet loss thresholds) and automatically triggering PSTN fallback when these parameters exceed predetermined limits. This approach maintains call quality through objective, measurable criteria while simplifying the decision-making process compared to complex manual monitoring systems.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring network quality parameters and using this information to automatically control trunk port status. When delay or packet loss exceeds thresholds, the system provides feedback to busy out the IP trunk ports, creating a closed-loop control system that maintains call quality without requiring complex manual intervention.
3Productivity
If call admission control is used to limit bandwidth for voice calls, then network resources are managed, but calls may be denied and forwarded to voice mail causing caller frustration
Solution Approach 1:
The system uses an intermediary approach by introducing PSTN as an alternate routing path when IP network bandwidth is exhausted. Instead of simply denying calls when bandwidth limits are reached, the system mediates between network resource constraints and call completion requirements by automatically switching to PSTN for overflow traffic, thereby maintaining call completion rates while still managing IP network resources effectively.
4Adaptability or versatility
If multiple separate system implementations are interconnected by traditional inter-switch trunking protocol, then peer-to-peer interconnection is enabled, but the architecture is limited and requires separate system implementations
Solution Approach 1:
The system implements universality by enabling a single media server to serve multiple functions and multiple enterprises through SIP-based virtual trunks. Instead of requiring separate peer-to-peer system implementations with dedicated trunks, the universal media server can handle calls across multiple enterprises over IP, with automatic PSTN fallback capability, thereby simplifying the architecture while maintaining versatility.
Data Source
AI summary
Methods and systems for supporting the alternate routing of calls between endpoints, such as session initiation protocol (SIP) endpoints, are provided. An inner gateway alternate route (IGAR) application is invoked when the primary, Internet protocol, communication network is overloaded or otherwise unable to handle a call. The IGAR application assigns incoming and outgoing trunks, and serves as a contact point for session managers in routing the trunk call.