Specifications

Table of
Contents
xv
Why does the IP phone use DOB format logo file instead of popular BMP, JPG and so on?
....................................................................................................................................................... 240
How to increase or decrease the volume? ........................................................................... 240
What will happen if I connect both PoE cable and power adapter? Which has the
higher priority? ............................................................................................................................ 240
What is auto provisioning? ........................................................................................................ 240
What is PnP? ................................................................................................................................ 240
Why doesn’t the IP phone update the configuration? ....................................................... 241
What do “on code” and “off code” mean? ........................................................................ 241
How to solve the IP conflict problem?.................................................................................... 241
How to reset the IP phone to factory configurations? ........................................................ 241
How to restore the administrator password? ........................................................................ 242
What are the main differences among T28P, T26P, T22P and T20P? ................................ 242
Appendix ................................................................................. 245
Appendix A: Glossary ........................................................................................................................ 245
Appendix B: Time Zones .................................................................................................................... 247
Appendix C: Configuration Parameters ........................................................................................ 250
Setting Parameters in Configuration Files............................................................................... 250
Basic and Advanced Parameters ........................................................................................... 250
Audio Feature Parameters ....................................................................................................... 356
Security Feature Parameters .................................................................................................... 363
Upgrading Firmware .................................................................................................................. 368
Resource Files .............................................................................................................................. 370
Troubleshooting .......................................................................................................................... 374
Configuring DSS Key................................................................................................................... 376
Appendix D: SIP (Session Initiation Protocol) ................................................................................. 393
RFC and Internet Draft Support ............................................................................................... 394
SIP Request .................................................................................................................................. 395
SIP Header ................................................................................................................................... 396
SIP Responses .............................................................................................................................. 397
SIP Session Description Protocol (SDP) Usage ........................................................................ 399
Appendix E: SIP Call Flows ................................................................................................................ 400
Successful Call Setup and Disconnect ................................................................................... 401
Unsuccessful Call Setup—Called User is Busy ........................................................................ 403
Unsuccessful Call Setup—Called User Does Not Answer .................................................... 407
Successful Call Setup and Call Hold ....................................................................................... 410
Successful Call Setup and Call Waiting ................................................................................. 412
Call Transfer without Consultation ........................................................................................... 417
Call Transfer with Consultation ................................................................................................. 421
Always Call Forward .................................................................................................................. 427
Busy Call Forward ....................................................................................................................... 430
No Answer Call Forward ............................................................................................................ 433
Call Conference ......................................................................................................................... 436