Cisco IP Phone Power Supplies Explained

We receive a lot of questions regarding Cisco IP phone power supplies, this article is an attempt to answer most of these questions. If it does not answer your question, please feel free to give us a call.

What is an IP phone power supply?

An IP Phone power supply is a device that supplies electrical power to an IP phone by plugging in to an AC wall jack. A power supply can also be referred to as a power adapter, power cube, power brick etc... Power cube is quite common with Cisco phones because the original Cisco model number for their IP phone power cube is CP-PWR-CUBE.
 

Do all Cisco IP phones come with a power supply?

The short answer is that most do not. This was Cisco's decision, not ours, but the only phones that include a power supply are the CP-7936 IP Conference Station, the CP-7920 Wireless IP Phone and the "CH2" versions of CP-7970/71 IP phones. All other Cisco IP phones do not include a power supply, one must be purchased along with the phone if it is needed.

The reason Cisco did not bundle power supplies with IP phones is because of a technology called Power Over Ethernet.  Power Over Ethernet delivers electrical power to the device through unused wires in a standard Ethernet cable (which is included with the phone). The device on the other end of the cable actually powers the phone, usually a switch or a power injector.  Cisco assumes at least some people will be using Power Over Ethernet with their IP phone and therefore it would be an unnecessary cost to those buyers.

For more information about Power Over Ethernet, please contact a sales representative.

What are the different types of Cisco IP phone power supplies?

There are six power supplies available for Cisco IP phones:

1)      CP-PWR-CUBE-3

2)      CP-PWR-CUBE-2

3)      CP-PWR-CUBE

4)      3RD-PWR-CUBE

5)      CP-7936-PWR-KIT

6)      CP-PWR-7920-NA

What is the difference between the CP-PWR-CUBE-3, CP-PWR-CUBE-2 and CP-PWR-CUBE?

The CP-PWR-CUBE is the original power supply for Cisco IP phones. It is the least expensive Cisco manufactured power supply option for the phones it is compatible with. The CP-PWR-CUBE is compatible with the following Cisco IP phones:

CP-7902G
CP-7905G
CP-7910G
CP-7910G+SW
CP-7912G
CP-7914 (expansion module)
CP-7940G
CP-7960G

This model also powers all earlier non G models of these IP phones. 

The CP-PWR-CUBE-2 was created to power the CP-7970G IP phone. This phone has a large color LCD display and the original CP-PWR-CUBE had problems powering it. Because of this Cisco replaced it with the CP-PWR-CUBE-2 model.

The CP-PWR-CUBE-2 is compatible with all of the IP phones that the CP-PWR-CUBE is compatible with as well as the CP-7970G.

The CP-PWR-CUBE-3 is a replacement for the CP-PWR-CUBE-2.  When Cisco released its newer version of IP phones like the CP-7941G, CP-7961G and CP-7971G it began using this power supply.  This power supply provides cleaner power to the phone and uses a longer plug to insert into the phone. Although this plug technically makes it more secure on the back of the phone, I have never had nor heard of any problems with the old plugs falling out.


What is the 3RD-PWR-CUBE?

The 3RD-PWR-CUBE is an aftermarket power supply designed specifically for Cisco IP phones.  Making power supplies isn't rocket science and it was only a matter of time before someone came out with an aftermarket power supply for these phones. There several varieties of aftermarket power supplies but some are questionable at best and definitely not manufactured for IP phones. We have found the 3RD-PWR-CUBE to be excellent and definitely recommend it if you want to save a few bucks and don't mind having non-Cisco parts.
 

The 3RD-PWR-CUBE is compatible with all Cisco IP phones except:

CP-7910G
CP-7910G+SW
CP-7936
CP-7920

What is the CP-7936-PWR-KIT?

The CP-7936-PWR-KIT is a power supply for the CP-7936 IP Conference Station.  The CP-7936 includes a power supply but if it is lost or damaged you would need to purchase this as a replacement.  The CP-7936-PWR-KIT is really a kit which includes several cables cords and ports which is why it is much more expensive than a regular IP phone power supply. For a picture of the CP-7936-PWR-KIT look at our product page.

Note: the CP-7936 can not be powered by any other power supply than the CP-7936-PWR-KIT and to my knowledge there have not been any aftermarket solutions for this device.

 
What is a CP-7920-PWR-NA?

The CP-PWR-7920-NA is a power supply for the Cisco CP-7920 Wireless IP Phone. The CP-7920 includes a power supply but if it is lost or damaged you would need to purchase this as a replacement. The CP-PWR-7920-NA is similar to a cell phone charger because it is a wall wart form factor and plugs directly into the AC. For a picture of CP-PWR-7920-NA look at our product page.

Note: the CP-7920 can not be powered by any other power supply than the CP-PWR-7920-NA and to my knowledge there have not been any aftermarket solutions for this device.

Which Power Supply Should I buy?

If you have a CP-7936 you need to use a CP-7936-PWR-KIT, if you have a CP-7920 you need to use a CP-PWR-7920-NA. But    if you have any other Cisco IP phone, there are options.

If you only want the newest Cisco recommended version and don't care about price go with the CP-PWR-CUBE-3.

If you're confused about all these power supplies and don't care about price - you can't go wrong with a CP-PWR-CUBE-3. It will power anything besides the CP-7936 or CP-7920.

If you want to save a few bucks but only want to use Cisco products, use the CP-PWR-CUBE if you're phone is compatible (see above).

If you don't mind using non-Cisco parts, go with the 3RD-PWR-CUBE if it's compatible with your phone (see above). It will save you a few bucks and it works fine.

Thomas Baxter
Voiplink.com