1、 VoLTE Implementation Guide September 2025 GSM Association VoLTE Implementation Guide Back to navigation Page 2 of 51 Navigation Introduction Business Drivers This section contains information that the MNO can use in its business plan to justify launching VoLTE roaming outbound and/or inbound.Select

2、ing Roaming Partners A summary of some key issues related to handsets and frequencies that will affect the selection of roaming partners and steering of roaming.Billing Issues Technical Issues for S8HR VoLTE Roaming VoLTE/IMS Issues Impacted by S8HR VoLTE Roaming Recommendations/solutions to VoLTE/I

3、MS related issues that are impacted by S8HR VoLTE roaming.SMSoIP Further details on SMSoIP covering;Service Enablement;Billing;and Message Flows.IMS Emergency Call for S8HR Inbound Roamers Regulatory Aspects of S8HR VoLTE Roaming Regulatory aspects that are impacted by S8HR VoLTE roaming.VoLTE/Roami

4、ng Testing Describes the ecosystem,methodology,profiles and test cases for VoLTE/Roaming testing.IR.21 Information related to VoLTE Roaming VoLTE Roaming Checklist GSM Association VoLTE Implementation Guide Back to navigation Page 3 of 51 VoLTE Implementation Guide 1 Introduction 5 1.1 Overview 5 1.

5、2 Scope 5 1.3 References 6 1.4 Acknowledgements 6 2 Business Drivers 7 2.1 Business drivers of VoLTE on Home Network 7 2.2 Business Drivers for VoLTE Roaming 8 2.2.1 Customer Experience 8 2.2.2 Coverage 8 2.3 Possible Business Case Justifications(quick bullet points)8 3 Selecting Roaming Partners-Ha

6、ndsets,Coverage,and Capacity Bands 10 3.1 Frequencies 10 3.2 Handsets 11 3.3 Device based Steering of Roaming 12 4 Billing Issues 13 4.1 Comparison of QCI-based charging and APN-based charging 13 4.2 Signalling 13 4.3 Retail Presentation 15 4.3.1 Billing from Home Network Elements 15 4.3.2 Time Zone