Cisco 7925G Administration Guide - Page 207

Chapter 10 Troubleshooting the Cisco Unified Wireless IP Phone 7925G Resolving Voice Quality and Roaming See the "VoIP WLAN Configuration" section on page 2-21 for more information. • Check your gateway and IP routing for voice problems. • Check if a firewall or NAT is in the path of the RTP packets. If so, you can use Cisco IOS and PIXNAT to modify the connections so that two-way audio is possible. • Check that the Data Rate setting for the phone and the access point are the same. These settings should match or the phone should be set for Auto. • Check the phone hardware to be sure the speaker is functioning properly. • Check the volume settings in the Phone Settings menu. Symptom: Improper Roaming and Voice Quality or Lost Connection If users report that when engaged in an active phone call and walking from one location to another (roaming), the voice quality deteriorates or the connection is lost, you can use the following suggestions to identify the cause of the problem. These sections can assist you with the following symptoms: • Voice Quality Deteriorates While Roaming, page 10-11 • Delays in Voice Conversation While Roaming, page 10-11 • Phone Loses Connection with Cisco Unified Communications Manager While Roaming, page 10-11 • Phone Does Not Roam Back to Preferred Band, page 10-12 Voice Quality Deteriorates While Roaming Check the RSSI on the destination access point to see if the signal strength is adequate. The next access point should have an RSSI value of -67 dBm or greater. Check the site survey to determine if the channel overlap is adequate for the phone and the access point to hand off the call to the next access point before the signal is lost from the previous access point. Check to see if noise or interference in the coverage area is too great. Check that signal to noise ratio (SNR) levels are 25 db or higher for acceptable voice quality. Delays in Voice Conversation While Roaming Use the Site Survey Utility on the Cisco Unified Wireless IP Phone 7925G to see if there is another acceptable access point as a roaming option. The next access point should have an RSSI value of 35 or greater to roam successfully. Check the Cisco Catalyst 45xx switch to see if it has the correct version of Supervisor (SUP) blades. The blades must be versions SUP2+ or higher to prevent roaming delays. Phone Loses Connection with Cisco Unified Communications Manager While Roaming Check for the following configuration or connectivity issues between the phone and the access point: • The RF signal strength might be weak. Use the Site Survey Tool and check the RSSI value for the next access point. • The next access point might not have connectivity to Cisco Unified Communications Manager. OL-15984-01 Cisco Unified Wireless IP Phone 7925G Administration Guide for Cisco Unified Communications Manager 7.0(1) 10-11