SIP Payload Identifier Translation for Reliable VoLTE Call Control

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Solution Overview

Problem

The lack of global compatibility among SIP endpoints in VoLTE deployments leads to issues with heterogeneous implementations, particularly in complex scenarios like call pickup and call transfer, where different media codecs can cause communication failures due to inconsistent payload identifier mappings.

Innovation Solution

A network entity, such as a SIP application server or session border controller, modifies payload identifiers in signaling messages to ensure consistent usage throughout a communication session by storing and translating payload identifiers independently of initial settings, ensuring compatibility between devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different media codecs are used by heterogeneous SIP endpoints, then device compatibility and media format diversity are improved, but communication reliability deteriorates due to inconsistent payload identifier mappings

Engineering Contradiction:
Improvemedia format compatibilityVSAvoidcommunication reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The network entity acts as an intermediary between SIP endpoints with different media codecs. It receives payload identifiers from both endpoints, stores them in association with each other, and translates between them. This mediator resolves the incompatibility by maintaining a mapping that allows seamless translation, ensuring reliable communication despite heterogeneous media formats.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the payload identifier parameter based on the communication context. When media is transmitted from a first endpoint to a second endpoint, the network entity translates the payload identifier to match the appropriate codec. This parameter transformation ensures that each endpoint receives media in its expected format while maintaining consistent internal mapping.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If payload identifiers are dynamically assigned without centralized coordination, then device autonomy and implementation flexibility are improved, but session consistency deteriorates in complex call scenarios

Engineering Contradiction:
Improvedevice autonomyVSAvoidsession consistency
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The network entity performs preliminary action by storing the payload identifier from the first endpoint before receiving media from the second endpoint. This advance preparation ensures that when the second endpoint sends media with its own payload identifier, the network entity can immediately translate it using the pre-stored mapping, maintaining session consistency without requiring real-time negotiation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system establishes a feedback loop where the network entity stores payload identifiers and uses them to guide translation decisions. The stored payload identifier acts as feedback information that informs the translation process, ensuring that the correct codec mapping is applied to maintain session consistency throughout the communication.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4351104B1Telecommunications network entity and method
Publication Date: 2026.02.04 VODAFONE GROUP SERVICES LTD
  • EP4351104B1 patent drawingFigure 1A~1C
  • EP4351104B1 patent drawingFigure 2~3
  • EP4351104B1 patent drawingFigure 4

AI summary

A method performed by a network entity of a telecommunications network is provided. The method comprises: receiving a first session initiation protocol, SIP, message originating from the calling device and addressed to the first called device, the first SIP message comprising a first set of one or more payload identifiers; receiving a second SIP message originating from the second called device and addressed to the calling device, the second SIP message comprising a second set of one or more payload identifiers; determining a third set of one or more payload identifiers based on at least one of the first set of one or more payload identifiers and the second set of one or more payload identifiers; and sending, to the calling device, a third SIP message, the third SIP message comprising the third set of one or more payload identifiers. A computer program, network entity and telecommunications network are also provided.