Hitless Call Agent Upgrade via Device Simulator Resynthesis
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Solution Overview
Problem
Cloud-based telephony systems face challenges in maintaining high reliability and seamless user experience during system updates, as frequent software updates can disrupt ongoing calls and prevent users from invoking features, unlike on-premise systems where upgrades are less frequent.
Innovation Solution
A cloud-based IP telephony system with an active/standby call agent pair and virtual IP infrastructure allows for hitless upgrades and high availability, using device simulator processes to resynthesize and re-establish calls without signaling to endpoints, ensuring continuous service and feature availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequent software updates are performed in cloud-hosted telephony systems, then system adaptability and code freshness are improved, but call stability and service continuity deteriorate
Solution Approach 1:
The system performs preliminary actions by creating a standby call agent instance with updated code before the active agent fails. The standby instance is pre-configured and ready to take over immediately when needed, allowing updates to be applied without disrupting active calls. This resolves the contradiction by preparing the system in advance for updates while maintaining current call stability.
Solution Approach 2:
The standby call agent acts as an intermediary between the active agent and the update process. When the active agent fails, the standby agent seamlessly takes over, mediating the transition and ensuring call continuity. This intermediary mechanism allows frequent updates to be applied to the standby instance without affecting the stability of active calls handled by the current active agent.
2Duration of action of stationary object
If call updates are performed during active calls, then service continuity is improved, but feature availability and user experience deteriorate
Solution Approach 1:
The system segments the call agent functionality into active and standby instances. The active instance handles ongoing calls and maintains feature availability, while the standby instance receives updates. This segmentation allows the system to maintain service continuity through the standby instance while preserving feature availability through the active instance, resolving the contradiction between continuity and usability during updates.
Data Source
AI summary
A method is provided in which a call agent process that supports one or more Internet Protocol (IP) calls, stores to persistent memory a set of data associated with the one or more IP calls. An outage is detected affecting the one or more IP calls. Using the data retrieved from the persistent memory, the one or more IP calls are resynthesized using a device simulator process to simulate connectivity with endpoints that were participating in the one or more IP calls prior to the outage. After resynthesizing, depending on activity detected from devices associated with the one or more IP calls, the one or more IP calls are internally re-stitched/re-establishing (without signaling to endpoints) with the endpoints involved in the one or more IP calls, or the one or more calls are fully re-stitched/re-established by signaling an endpoint that was participating in the one or more IP calls.