Cisco IP phones Boot sequence

BOOT SEQUENCE
1. Obtaining Power from the Switch.	You can connect the Cisco IP Phone to a Cisco Catalyst switch with one of the modules that provides power to the phone (WS-X6348-RJ45V).
	If you use this optional configuration, the phone receives phantom power and powers up when you connect the Cisco IP Phone to the switch. The phone then sends Cisco Discovery Protocol (CDP) notifications to the switch indicating that it is ready to receive CDP packets and indicating the power requirement for the phone. The switch allocates power and sends it over the network cable.
1. Loading the Stored Phone Image.	The Cisco IP Phone has non-volatile Flash memory in which it stores firmware images and user-defined preferences. At startup, the phone runs a bootstrap loader that loads a phone image stored in Flash memory. Using this image, the phone initializes its software and hardware.
1. Configuring VLAN.	If the Cisco IP Phone is connected to a Cisco Catalyst switch, the switch next informs the phone of the voice VLAN defined on the switch. The phone needs to know its VLAN membership before it can proceed with the Dynamic Host Configuration Protocol (DHCP) request for an IP address.
1. Obtaining an IP Address.	If the Cisco IP Phone is using DHCP to obtain an IP address, the phone queries the DHCP server to obtain one. If you are not using DHCP in your network, you must assign static IP addresses to each phone locally.
1. Accessing a TFTP Server.	In addition to assigning an IP address, the DHCP server directs the Cisco IP Phone to a TFTP Server. If the phone has a statically-defined IP address, you must configure the TFTP server locally on the phone; the phone then contacts the TFTP server directly.
1. Requesting the CTL file.	Before requesting a configuration file, a phone accesses a CTL file. If you want a phone to use security features, the CTL file should be available.
	For information about creating the CTL file, refer to Cisco CallManager Security Guide.
1. Requesting the Configuration File.	The TFTP server has configuration files, which define parameters for connecting to Cisco CallManager and other information for the phone.
1. Contacting Cisco CallManager.	The configuration file defines how the Cisco IP Phone communicates with Cisco CallManager. After obtaining the file from the TFTP server, the phone attempts to make a connection to the highest priority Cisco CallManager on the list. If security is implemented, the phone makes a TLS connection. Otherwise, it makes a non-secure TCP connection.
	If the phone was manually added to the database, Cisco CallManager identifies the phone. If the phone was not manually added to the database and auto-registration is enabled in Cisco CallManager, the phone attempts to auto-register itself in the Cisco CallManager database.
	Note : Auto-registration must be disabled if security is implemented.
	Cisco CallManager informs devices using .cnf format configuration files of their load ID. Devices using .xml format configuration files receive the load ID in the configuration file.