show port inlinepower or show port inlinepower mod/port for a specific portIf you run out of power on the switch, you should see a message logged to the console, as------------------------------------------------------------------------------------------well as your Syslog server if you have one configured, that states%SYS-3-PORT_NOPOWERAVAIL:Device on port 5/12 will remain unpowereda defective IP Phone causes this type of behavior, although cabling problems can cause problems like this as wellespecially cable runs that exceed the Ethernet maximum distance of 100 meters.If the switch provides power to a port but does not detect the link within five seconds, youwill see this message:-------------------------------------------------------------------------------------------------------------------%SYS-3-PORT_DEVICENOLINK:Device on port 5/26 powered but no link upIn review, it is important to follow this basic procedure when troubleshooting inline power issues:Step 1If you suspect that the IP Phone doesnt work, plug it into a known good port.Step 2If you suspect that the port or cable might be bad, plug in a known good IP Phone.Step 3With this information, investigate any physical layer possibilities, such as cables not being plugged in, damaged cables, or cables not patchedthrough correctly to the switch port.Step 4Check configuration and power issues on the switch itself. Make sure that the switch is in Auto mode and that the port in question hasnt been setto Off. Also check that sufficient power is available for the IP Phone. Once the IP Phone is powered up, ensure the IP addressing information on the IP Phone iscorrect.Troubleshooting Connectivity and Skinny Registration:================================================================1) Verify the VLAN in the phone.2)Once the IP Phone has determined the proper VLAN ID for voice packets, it must obtain the IP addressing information.This can be accomplished by either statically configuring all the IP addressing parameters or via DHCP.UNABLE TO GET THE IP ADDRESS FOR THE PHONE:--------------------------------------------If your IP phone is not able to obtain an IP address via DHCP, check for any networkconnectivity problems between the IP phone and the DHCP server.If the DHCP server is not on the same subnet as the IP phone voice VLAN, ensure that you have properlyconfigured an IP helper address on the local router (using the command ip helper-address x.x.x.x on the LAN interface)If your IP Phone is still unable to obtain an IP address via DHCP, the next thing to try is toreset the phone to its factory default configuration and then hard-code (manually enter) all the necessary IP parametersTFTP TROUBLESHOOTING:=====================Note: The first thing the IP Phone does after it has its IP addressing information is request a file from the TFTP server called OS79XX.txt.The file OS79XX.txt conatins the name of the phone firmware to be loaded for e.g P0S30100 (without the extension .bin)P0S30100.binThis is the SIP image( Here P denotes the phone, 0 means that it is a combined image (application and DSP), S for SIP 0 for SCCP M for MGCP, 3-ARM Processor)The above file is used to determine whether to boot up as a Session Initiation Protocol (SIP), Media Gateway Control Protocol (MGCP), or Skinny protocol phone