Section 11.5: VOIP Verification
Although you might encounter a wide variety of IP Telephony problems, this section details some of the more common issues to check.
11.5.1: Verifying Inline Power
You can verify the inline power status for a switch port with the following EXEC command:
Switch# show power inline [type mod/num]
The example below provides some sample output from this command:
11.5.2: Verifying Voice VLANs
Verifying the operation of the link between a switch port and an IP Phone is not easy. This is because the link can operate as a special-case, two-VLAN 802.1Q trunk, but the link never appears to be trunking according to any IOS show commands.
First, you should determine if the switch and IP Phone are actually communicating. Use the following EXEC command to see if the phone has advertised itself to the switch:
Switch# show cdp neighbors type mod/num detail
Next, verify the access VLAN being used on the switch port, along with the voice VLAN (if any).
You can find these values with the following EXEC command:
Switch# show interface type mod/num switchport