Starting up a new or used wireless Cisco IP Phone is painless and easy. Here are the main steps to take when starting a Cisco IP Phone.
- Obtain Power From the Cico Switch Using FLP: If you are using a Cisco switch that’s able to provide Cisco inline power, the switch will transmit a FLP signal (Fast Link Pulse). This Cisco switch (new or used) uses FLP to identify whether or not the attached device is an unpowered Cisco IP Phone. In the unpowered state, a Cisco IP Phone loops back the FLP, telling the switch to send -48 V DC power down the line.
- Load the stored phone “image”: New and used Cisco IP wireless phones have nonvolatile Flash memory. This memory stores firmware “images” as well as user-defined preferences. Upon startup, the phone runs a “bootstrap loader” that loads a phone image stored in Flash memory. Using this image, the phone then initializes its hardware and software.
- Configure VLAN: After your Cisco Wireless IP Phone receives power and loads, the switch transmits a Cisco Discovery Protocol packet to the IP Phone. Assuming that voice VLAN has been configured, this Cisco Discovery Protocol packet provides the IP Phone with VLAN information.
- Obtain IP address and TFTP server address: The new or used Cisco IP Wireless Phone then broadcasts a request to a DHCP server. The DHCP server in turn responds to the IP Phone with an IP address, a subnet mask, and the IP address of the Cisco TFTP, among other things.
- Contact the TFTP server for configuration: The Cisco IP Wireless Phone then tries to reach the Cisco TFTP server. The TFTP server has configuration files (.cnf file format or .cnf.xml) for telephony devices, which in turn defines parameters for connecting to Cisco CallManager. The TFTP server then transmits the configuration information for that IP Phone, containing an ordered list of up to three Cisco CallManagers. Normally, any time you make a change in Cisco CallManager which would require a phone (device) to be reset, a change will have been made to the configuration file of that phone. If a phone has an XML-compatible load, it requests an XMLDefault.cnf.xml format configuration file; otherwise, it requests a .cnf file.
If you’ve enabled auto-registration in Cisco CallManager, the phones can then access a default configuration file (sepdefault.cnf.xml) from the TFTP server. However, if you manually entered the phones into the Cisco CallManager database, the phone accesses a .cnf.xml file that corresponds to its device name. The .cnf.xml file in turn has information which lets the phone know which image load that it should be running. If this image load differs from the one that is currently loaded on the phone, the phone will contact the TFTP server to request the newer image file, stored in a .bin format.
- Register with Cisco CallManager: Upon obtaining the file from the TFTP server, the phone attempts to make a TCP connection to the highest-priority Cisco CallManager on the list.
About Network I.T. and Cisco IP Wireless Phones
In addition to Network IT buying used Cisco IP phones, it also offers the following used Cisco wireless IP phones for your business:
- Used Cisco CP-7961G
- Used Cisco CP-7942G
- Used Cisco CP-7962G
Network IT is located in Toronto, Ontario and ships throughout Canada and the US. Contact Network IT today to get a free quote on Used Cisco IP and Wireless Phones.