8 Troubleshooting the Cisco IP Phone

General Troubleshooting Tips for the Cisco IP PhoneChapter 8 Troubleshooting the Cisco IP PhoneTable 8-2Cisco IP Phone Troubleshooting (continued)SummaryGaps in voice calls.Checking signaling.Checking the handset cradle clip.Checking the hook switch contacts.ExplanationCheck the AvgJtr and the MaxJtr statistics. A large variancebetween these statistics might indicate a problem with jitter onthe network or periodic high rates of network activity.See the “Call Statistics Screen” section on page 6-17 forinformation about displaying these statistics.To check that signaling is working properly between the phoneand Cisco CallManager, press the Speaker button on the phoneto answer a call. If you can answer a call and if you hear a dialtone, signaling is working properly.Cisco IP Phones are designed with a reversible cradle clip in thehandset. This clip is used with the plastic tab protruding outwhen the phone is in a vertical (wall-mounted) position. Theposition of the tab can interfere with the handset as it is placedin the cradle. If the phone remains in the on-hook position youmay experience continued ringing when you try to answer a callor a lack of dial tone when you try to place a call. To resolvethis problem, you may need to reverse the clip.If the handset cradle clip is in the wall-mounted position andyour phone is placed on a desktop, slide the clip upward toremove it. Rotate the clip 180 degrees and slide it back in so thatthe tab is hidden.If the hook switch remains in the down position, tapping on thephone should free up the switch. You can also try pushing andsuddenly releasing the off-hook button after the handset hasbeen picked up.The hook switch contacts on the phone use a wiping action toself-clean the contacts. If your phone is not used regularly, dustand other airborne contaminants may degrade the contactperformance and cause problems with operation. If you haveperiods of limited phone usage, you can clean the contacts byquickly pressing and releasing the hook switch a dozen times.8-16Cisco IP Phone Administration Guide for Cisco CallManager 4.1OL-4825-02