Modified SIP Response for VoLTE Legacy Compatibility
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Solution Overview
Problem
Ensuring backwards-compatibility with legacy devices in VoLTE communication sessions is challenging, particularly regarding local ringing tone generation and compatibility with fixed SIP phones.
Innovation Solution
The introduction of a modified SIP response message with additional data, such as a Combined User-Agent header, that includes information about the calling and called devices, allowing network entities to take remedial action without querying external databases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a 183 session progress message with SDP is sent in VoLTE, then voice and data capacity is improved, but legacy fixed SIP phones cannot generate local ringing tones due to missing RTP
Solution Approach 1:
A new header field (P-Early-Media) is introduced as an intermediary mechanism to convey early media information between VoLTE devices and legacy SIP phones. This header acts as a mediator that translates VoLTE's RTP-based early media into a format understandable by legacy devices, enabling them to generate local ringing tones without requiring actual RTP stream transmission.
Solution Approach 2:
The patent modifies the SIP protocol by adding a new parameter (P-Early-Media header field) that changes the information exchange parameters between VoLTE and legacy devices. This parameter change allows legacy devices to infer early media capability and adjust their ringing tone generation behavior accordingly, resolving the compatibility issue without altering core VoLTE functionality.
2Reliability
If exhaustive end-to-end tests are performed with all possible combinations of handsets, then interoperability is improved, but implementation complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by establishing standardized header field formats and information exchange mechanisms before deployment. By pre-defining how devices should exchange capability information through standardized headers, the need for exhaustive pairwise testing is reduced, as devices can automatically negotiate compatibility through these pre-established protocols.
3Reliability
If local ringing tone generation is changed in IR.92, then VoLTE quality is improved, but backwards compatibility with legacy devices is lost
Solution Approach 1:
The patent introduces dynamic adaptability by enabling devices to adjust their behavior based on the presence or absence of the P-Early-Media header. VoLTE devices can dynamically switch between standard RTP-based early media and header-based early media indication depending on whether the remote device supports the new header, thereby maintaining both quality and backwards compatibility.
Data Source
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AI summary
The disclosure relates to a method for facilitating a communication session between a calling device (101) and a called device (102). The method comprises generating, by a first entity (103a), a modified SIP response including additional data. The modified SIP response is a response to a SIP request made by the calling device (101). The additional data comprises an indication of at least one characteristic of at least one of the calling device (101) and the called device (102). The method further comprises receiving, at a second entity (103b), the modified SIP response. The method also comprises applying, by the second entity (103b), one or more rules to the modified SIP response based on the additional data.