If you are using Cisco solutions in your phone and network infrastructure, there are several methods that can help you to save energy and reduce your electricity costs. In this article you can find how to save energy in your IP phone & network infrastructure.
As you know, unlike analog phones, IP phones require a power supply to work. They can get their power even from power adapters or network devices that can give power through PoE.
What is PoE?
PoE is an abbreviation for Power over Ethernet. In a very simple sense, PoE is a protocol which is defined by EEE 802.3af (15.4W max.) And 802.3at (30W max.) standards and it enables devices (IP phones, wireless APs. etc.) to get their power through a network cable.
Since IP telephones do not need much energy, they can easily work with the 802.3af standard. In this standard, devices are classified according to their power requirements. You can find these classes and power requirements in the following table:
| 802.3af Class | Max. Power (W) |
| 3 | 15.4 |
| 2 | 7 |
| 1 | 4 |
| 0 | 15.4 |
The following table shows typical and maximum power consumption of current Cisco IP phones:
| Model | 802.3af Class | Idle (W) | Maximum (W) |
| 7811 | 1 | 2.6 | 3.8 |
| 7821 | 1 | 2.6 | 3.8 |
| 7841 | 1 | 2.6 | 3.8 |
| 7861 | 1 | 2.6 | 3.8 |
| 8811 | 2 | 3.9 | 6.5 |
| 8841 | 2 | 3.9 | 6.5 |
| 8845 | 2 | 3.9 | 6.4 |
| 8851 | 4 | 3.9 | 9.8 |
| 8861 | 4 | 4.2 | 14.2 |
| 8865 | 4 | 4.2 | 14.7 |
What About Savings With IP Phone?
Cisco IP phones that work with CUCM have two different energy saving modes, Power Save and Power Save Plus. Now let’s examine them in detail:
IP Phone – Power Save Mode
In this mode, the display’s backlight does not light when the phone is not in use and the phone remains registered with the CUCM, can receive incoming calls, and also users can make calls. The CUCM phone configuration menu (CUCM Administration > Device > Phone > related phone) has special configuration options to manage background lighting on certain days, at a specified time interval, and when the phone is not used for a certain period of time. You can find these configuration options and descriptions below:
| Option | Explanation |
| Days Display Not Active | Specifies the days which the screen is not turned on. You can select the day which the screen is off from the list. Hold down the Ctrl key for multiple selections. |
| Display On Time | Specifies the time at which the display will be turned on. This field should be written in 24-hour format. For example, if you want it to open at 8:30 in the morning, you should type 08:30. If this field is left blank, the screen will turn on at 0:00. |
| Display On Duration | Specifies the length of time the display stays on. For example, if you enter 08:00, the phone display will remain on until 16:30 with the configuration above. If no information is entered in this field, the display will remain on until midnight. |
| Display Idle Timeout | Specifies how long after which the display turns off when the phone is not in use. If you want it to close after 1 hour idle, just enter 01:00. |
Note 1: In Power Save mode, the phone exits the power saving mode when the user lifts the handset or press any button when the phone’s display or backlight is off.
Note 2: 7811 series phones do not support energy saving in Power Save mode because they do not have backlight.
As you can see in the second table, there is about 30% difference between the idle and max amount of power they draw. Therefore, using Power Save mode can save approximately 20% energy with a very rough calculation. You also do not need extra hardware software or licenses to implement this mode.
Power Save Plus Mode (EnergyWise)
In the Power Save Plus mode, the phones go to sleep in the specified time or day, as in power save mode. In this case, incoming calls cannot be received because the phones do not register to the CUCM, and users must press the Select key and wake the IP phone to make calls. The advantage is that the energy consumption in sleep state is 1W.
Note: Power Save Plus mode is offered as part of a solution called Cisco Energy Management Suite and needs to be supported by switches on your network. Your CUCM version needs to be 8.6 and higher, and the firmware version of the phones needs to be 9. (2) 1 and higher.
Likewise, the CUCM phone configuration menu for Power Save Plus configuration has special configuration options to manage the sleep mode on specific days, at a specified time interval, and when the phone is not used for a certain period of time. You can find these configurations and descriptions below:
| Option | Explanation |
| Enable Power Save Plus | Sets the days on which this feature will be activated. You can select multiple days by holding down the Ctrl key. |
| Phone On Time | Specifies the time at which the phone is switched on. If you want it to open at 7:30 in the morning, you must enter 07:30. |
| Phone Off Time | Sets the time at which the phone goes to sleep. If you want to go to sleep at 6:00 in the evening, you must enter 18:00. |
| Phone Off Idle Timeout | Determines how long it takes for the phone to go to sleep inactive. This feature is active in the following situations: If the phone is woken up during Off Time (with the select key). If the phone is awakened by the switch. If the time has come off but the phone has continued to be used. |
| Enable Audible Alert | When activated, the phone emits an audible tone (ringing tone) 10 minutes before it goes into sleep mode. |
| EnergyWise Domain | The EnergWise domain name where the phone is located. |
| EnergyWise Secret | The password that the phone uses to talk to devices in the EnergyWise domain. |
| Allow EnergyWise Overrides | Determines whether policies printed from the EnergyWise controller have priority over the CUCM configuration. |
Last Words
In terms of energy saving, Pover Save and Power Save Plus modes provide a great advantage for organizations which has Cisco IP phone infrastructure, and they can easily be applied. In this way, you can reduce operational costs by increasing energy efficiency.