Emergency Call Routing via Over-The-Top Services
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Solution Overview
Problem
In areas where Voice over Long Term Evolution (VoLTE) and Circuit Switched Fallback (CSFB) are not available, users face challenges in making normal or emergency calls due to gaps in coverage, especially in rural areas where LTE has a longer range but VoLTE is not deployed, and non-VoLTE capable devices cannot make calls outside 2G or 3G coverage.
Innovation Solution
User Equipment (UE) receives network indications about the availability of carrier-grade voice over cellular packet data calls and over-the-top (OTT) services, allowing it to automatically or programmatically route voice calls, including emergency calls, via OTT services when VoLTE and CSFB are not available, using LTE data connections and location information for correct routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If LTE coverage is extended to rural areas, then coverage area is improved, but voice call capability deteriorates when VoLTE is not deployed
Solution Approach 1:
The patent introduces an intermediary mechanism (network indication signaling) that informs the UE about the availability of voice services in the current cell. This intermediary information allows the UE to make intelligent routing decisions, selecting appropriate voice service paths (VoLTE, CSFB, or OTT) based on network capabilities, thereby maintaining voice call reliability in extended LTE coverage areas where traditional voice services may not be available.
2Ease of operation
If UE attempts to make calls in areas without VoLTE/CSFB coverage, then call initiation is attempted, but call establishment fails
Solution Approach 1:
The patent implements preliminary action by having the network proactively provide indication signaling to the UE about voice service availability before the UE attempts to establish a call. This advance information allows the UE to pre-determine the appropriate call routing method (VoLTE, CSFB, or OTT service), ensuring that call establishment can proceed successfully without attempting failed connection methods first.
3Adaptability or versatility
If UE uses OTT services for voice calls, then voice service availability is improved in coverage gaps, but service reliability deteriorates due to lack of native UE support
Solution Approach 1:
The patent introduces an intermediary indication mechanism that informs the UE when OTT services are available as a fallback option. This intermediary signaling allows the UE to reliably select OTT services only when appropriate (when VoLTE and CSFB are unavailable), thereby maintaining service reliability through intelligent routing decisions rather than blindly relying on OTT services.
4Measurement precision
If network provides detailed service availability indications, then call routing accuracy is improved, but signaling complexity increases
Solution Approach 1:
The patent applies local quality by providing specific, localized indication information about voice service availability in each cell rather than general network-wide announcements. The indication signaling contains precise, cell-specific information about whether VoLTE, CSFB, or OTT services are available, allowing the UE to make accurate routing decisions for its current location without processing unnecessary network-wide signaling information.
Data Source
AI summary
Methods and apparatus, including computer program products, are provided for emergency call handling. In one aspect there is provided a method. The method may include receiving, at a user equipment, an indication from a network, the indication representative of at least one of whether a carrier grade voice over cellular packet data call is available at a cell serving the user equipment or whether an over-the-top service is available at the cell serving the user equipment; and initiating, by the user equipment based on the received indication from the network, a call via the over-the-top service, when the indication represents the carrier grade voice over cellular packet data call is not available at the cell serving the user equipment and the over-the-top service is available at the cell serving the user equipment. Related apparatus, systems, methods, and articles are also described.