VoLTE - Voice over LTE (4G) ============================ .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is VoLTE?** VoLTE (Voice over LTE) is a technology that enables voice calls over the LTE (4G) data network instead of traditional circuit-switched networks. It uses the IP Multimedia Subsystem (IMS) to deliver voice, video, and messaging services over IP. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Why is VoLTE useful?** * High-quality voice (HD Voice) with lower latency. * Simultaneous voice and data over LTE. * Efficient spectrum use by eliminating the need for fallback to 2G/3G. * Supports rich communication services (RCS) like video calling, file sharing, etc. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How it works?** * Call Initiation: The UE (User Equipment) sends a SIP INVITE via IMS. * Session Setup: IMS core handles SIP signaling and negotiates media via SDP. * Bearer Setup: The EPC (Evolved Packet Core) sets up dedicated bearers for voice. * Call Management: SIP messages manage call progress, hold, transfer, etc. * Call Termination: SIP BYE ends the session, and bearers are released. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Where is VoLTE used?** * 4G LTE networks for voice and video calling. * IMS Core for managing multimedia sessions. * EPC (Evolved Packet Core) for bearer management. * RCS services for enhanced messaging and media sharing. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Which OSI layer does VoLTE belong to?** * Layer 7 (Application) - SIP (Session Initiation Protocol), SDP (Session Description Protocol), RTP (Real-Time Transport Protocol) * Layer 6 (Presentation) - Codec negotiation (e.g., AMR-WB for HD Voice), media format handling * Layer 5 (Session) - SIP session control, call setup/teardown, registration * Layer 4 (Transport) - UDP (for SIP, RTP), TCP (for some IMS interfaces), SCTP (for Diameter) * Layer 3 (Network) - IP (IPv4/IPv6) for routing packets * Layer 2 (Data Link) - LTE MAC, RLC, PDCP layers * Layer 1 (Physical) - LTE PHY layer (radio transmission) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`VoLTE Version&RFC Details ` * :ref:`VoLTE Basic Setup on Ubuntu using IPv4 ` * :ref:`VoLTE Basic Setup on Ubuntu using IPv6 ` * :ref:`VoLTE Protocol Packet Details ` * :ref:`VoLTE Usecases ` * :ref:`VoLTE Basic Features ` * :ref:`VoLTE Feature : High-Defnition (HD) Voice ` * :ref:`VoLTE Feature : All-IP Architecture ` * :ref:`VoLTE Feature : Fast Call Setup ` * :ref:`VoLTE Feature : Simulataneous Voice & Data ` * :ref:`VoLTE Feature : Improved Battery Life ` * :ref:`VoLTE Feature : Seamless Handover (SRVCC) ` * :ref:`VoLTE Feature : QoS Support ` * :ref:`VoLTE Feature : Emergency Services Support ` * :ref:`VoLTE Feature : IMS-Based Services ` * :ref: `VoLTE Feature : Roaming Support ` * :ref:`Reference links ` .. _VoLTE_step1: .. tab-set:: .. tab-item:: Learnings in this section * In this section, you are going to learn .. _VoLTE_step2: .. tab-set:: .. tab-item:: Terminology * Terminology .. _VoLTE_step3: .. tab-set:: .. tab-item:: Version Info * Version Info .. _VoLTE_step5: .. tab-set:: .. tab-item:: VoLTE Version&RFC Details .. csv-table:: :file: ./VoLTE/VoLTE_rfc_details.csv :widths: 10,10,10,30 :header-rows: 1 .. _VoLTE_step20: .. tab-set:: .. tab-item:: VoLTE Basic Setup on Ubuntu using IPv4 * Setup .. _VoLTE_step21: .. tab-set:: .. tab-item:: VoLTE Basic Setup on Ubuntu using IPv6 * Setup .. _VoLTE_step6: .. tab-set:: .. tab-item:: VoLTE Protocol Packet Details **SIP INVITE Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet1_details.csv :widths: 10,20,30,10 :header-rows: 1 **SIP 200 OK Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet2_details.csv :widths: 10,20,30,10 :header-rows: 1 **SIP ACK Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet3_details.csv :widths: 10,20,30,10 :header-rows: 1 **RTP Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet4_details.csv :widths: 10,20,30,10 :header-rows: 1 **SIP BYE Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet5_details.csv :widths: 10,20,30,10 :header-rows: 1 **Bearer Setup (S1-AP) Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet6_details.csv :widths: 10,20,30,10 :header-rows: 1 **Diameter (Gx/gy/Cx) Packet** .. csv-table:: :file: ./VoLTE/VoLTE_packet7_details.csv :widths: 10,20,30,10 :header-rows: 1 .. _VoLTE_step7: .. tab-set:: .. tab-item:: VoLTE Usecases .. csv-table:: :file: ./VoLTE/VoLTE_usecases.csv :widths: 10,20,30 :header-rows: 1 .. _VoLTE_step8: .. tab-set:: .. tab-item:: VoLTE Basic Features .. csv-table:: :file: ./VoLTE/VoLTE_features.csv :widths: 10,10,30 :header-rows: 1 .. _VoLTE_step9: .. tab-set:: .. tab-item:: VoLTE Feature : High-Defnition (HD) Voice **High-Defnition (HD) Voice - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature1_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step10: .. tab-set:: .. tab-item:: VoLTE Feature : All-IP Architecture **All-IP Architecture - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature2_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step11: .. tab-set:: .. tab-item:: VoLTE Feature : Fast Call Setup **Fast Call Setup - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature3_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step12: .. tab-set:: .. tab-item:: VoLTE Feature : Simulataneous Voice & Data **Simulataneous Voice & Data - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature4_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step13: .. tab-set:: .. tab-item:: VoLTE Feature : Improved Battery Life **Improved Battery Life - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature5_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step14: .. tab-set:: .. tab-item:: VoLTE Feature : Seamless Handover (SRVCC) **Seamless Handover (SRVCC) - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature6_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step15: .. tab-set:: .. tab-item:: VoLTE Feature : QoS Support **QoS Support - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature7_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step16: .. tab-set:: .. tab-item:: VoLTE Feature : Emergency Services Support **Emergency Services Support - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature8_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step17: .. tab-set:: .. tab-item:: VoLTE Feature : IMS-Based Services **IMS-Based Services - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature9_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step18: .. tab-set:: .. tab-item:: VoLTE Feature : Roaming Support **Roaming Support - Testcases** .. csv-table:: :file: ./VoLTE/VoLTE_feature10_test_cases.csv :widths: 10,10,30,20 :header-rows: 1 .. _VoLTE_step19: .. tab-set:: .. tab-item:: Reference links * Reference links