To enable telnet on cisco switch , you need to configure following things :

• line vty 0 4
• password for login ( without pass you can not enable telnet)

Commands:

ESW2#configure t
Enter configuration commands, one per line.  End with CNTL/Z.
ESW2(config)#line vty 0 4
ESW2(config-line)#password cisco
ESW2(config-line)#login
ESW2(config-line)#end