Rob Huffman Sun, 04/06/2008 - 07:36
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Hi Sudeesh,


If you are using a non-Cisco switch that provides 802.3af PoE. The problem is that the 7940 and other older Cisco phones use a pre-standard power and not 802.3af PoE which the manufacturers use.


Q. What IP phone models support the Cisco pre-standard method of powered device detection?


A. These Cisco IP phones can accept Cisco pre-standard PoE from a card integrated with a Cisco Catalyst switch or a Catalyst in-line power patch panel:


7985G

7960G

7940G

7910G

7910G + SW

7912G

7905G

7902G

These phones can draw local power from a power cube (CP-PWR-CUBE-2=) in addition to a country or regionally specific power cord (CP-PWR-CORD-xx=).



Q. What IP phone models support the IEEE standard method of powered device detection?


A. These Cisco IP phones support IEEE 802.3af PoE:


7961G-GE

7971G-GE

7931G

7911G

7941G-GE

Note: These Cisco IP phones support both the Cisco pre-standard PoE and IEEE 802.3af PoE:


7970G

7961G

7941G

7906G


From this new doc;


Power over Ethernet (PoE) Power Requirements FAQ


http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00808996f3.shtml



You probably need a third party product like;


http://www.microsemi.com/PowerDsine/Products/Midspan/Splitters/



Hope this helps!

Rob

Justin Brenton Sun, 04/06/2008 - 10:05
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Hi Sudeesh,


If you are adding phones to a Cisco Switch that is currently providing power to phones then you may have reached your limitation to your POE supply.


You can disable POE on trunkports or ports not utilizing power by setting "power inline never" to the port on the switch.


You can also change the default allocated wattage to the switchport. The default is 15.4 watts per device.


Also please see the link below to calculate how much power you will need for your IP phones. This is a great tool.


http://tools.cisco.com/cpc/launch.jsp


Please let us know more information about your situation and we can provide a better solution for your needs.


HTH,

Justin

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