Yealink SIP-T4X Administrator's Manual page 15

Why do I get poor sound quality during a call? ................................................................ 243
What is the difference between a remote phone book and a local phone book? ....... 244
What is the difference between user name, register name and display name? .......... 244
How to reboot IP phone remotely? ..................................................................................... 244
How to increase or decrease the volume? ........................................................................ 244
What will happen if I connect both PoE cable and power adapter? Which has the higher
priority? .................................................................................................................................. 245
What is auto provisioning? .................................................................................................. 245
What is PnP? .......................................................................................................................... 245
Why doesn't the IP phone update the configuration?....................................................... 245
What do ―on code‖ and ―off code‖ mean?........................................................................ 245
How to solve the IP conflict problem? ................................................................................ 246
How to reset your phone to factory configurations? ......................................................... 246
How to restore the administrator password? .................................................................... 247
Appendix .......................................................................... 249
Appendix A: Glossary ................................................................................................................. 249
Appendix B: Time Zones ............................................................................................................. 251
Appendix C: Configuration Parameters .................................................................................... 254
Setting Parameters in Configuration Files .......................................................................... 254
Basic and Advanced Feature Parameters ......................................................................... 254
Audio Feature Parameters................................................................................................... 365
Upgrading Firmware............................................................................................................ 377
Resource Files ....................................................................................................................... 380
Troubleshooting .................................................................................................................... 385
Configuring DSS Key ............................................................................................................ 387
Appendix D: SIP (Session Initiation Protocol) ............................................................................ 403
RFC and Internet Draft Support .......................................................................................... 403
SIP Request ............................................................................................................................ 406
SIP Header ............................................................................................................................ 406
SIP Responses ....................................................................................................................... 408
SIP Session Description Protocol (SDP) Usage .................................................................. 410
Appendix E: SIP Call Flows ......................................................................................................... 411
Successful Call Setup and Disconnect ............................................................................... 412
Unsuccessful Call Setup—Called User is Busy .................................................................. 414
Unsuccessful Call Setup—Called User Does Not Answer ................................................ 417
Successful Call Setup and Call Hold .................................................................................. 419
Successful Call Setup and Call Waiting ............................................................................. 421
Call Transfer without Consultation ...................................................................................... 426
Call Transfer with Consultation ............................................................................................ 430
Always Call Forward ............................................................................................................ 435
Busy Call Forward ................................................................................................................ 439
No Answer Call Forward ..................................................................................................... 442
Call Conference.................................................................................................................... 445
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