What's the protocol between IP phone & Call manger ?

there are two protocol : sccp and sip

in the older version of call manager cisco prefered sccp, but now they encourage to use sip

TFTP is used to upload firmeware and configuration

Skinny Client Control Protocol (SCCP) SCCP uses Cisco-proprietary messages to communicate between IP devices and Cisco Call Manager.

We can also connect phones via SIP 

To Connect Cisco IP Phones with the CUCM there are the following 

1.SCCP- Skinny call control protocol

2. SIP- Session Initiation Protocol.

To get and update configuration files or firmwares phone uses

1. TFTP protocol on port udp

2. HTTP protocol (on modern firmwares) port tcp is used as backup protocol when TFTP doesn't work properly or blocked

To Connect Cisco IP Phones with the CUCM , we have two protocols these are :

1.SCCP- Skinny call control protocol

2. SIP- Session Initiation Protocol.

Now a days all the IP phones are moving towards SIP , as its call processing is fast.

cisco uses sccp for cisco phones and SIP for non cisco phones you can configure SIP for cisco phones

but non cisco devices doesn't support sccp

sccp skinney call control protocol