My cisco 7941 phone, all the lights are lid up but not working. Nothing in the display also

SOURCE: lost my user manual for

You can go to the link below to get the manual for the 7900 series

http://cisco.com/en/US/products/hw/phones/ps379/tsd_products_support_maintain_and_operate.html

SOURCE: CISCO 7941 IP PHONE disconnect you out after certain time

Unfortunately this is a very common problem with Cisco's IP Phones. It can be caused by either a faulty hookswitch or a damaged jack. Both of these problems can be remedied by contacting IdacomUSA.

SOURCE: CISCO IP PHONE 7941 -add background images (user preferences,

See Cisco's user guide regarding template modification and customization at http://www.ciscosystems.am/en/US/docs/voice_ip_comm/cuipph/7960g_7940g/7_0/sip/english/administration/guide/7960usrS.pdf

SOURCE: Can I use a CISCO IP 7941 phone, that has been on

you cannot connect these phones to a home phone line they can only be connected to a network, and you will eather need to load the SIP firmware on the phone and have a SIP provider or use a call centre manager such as Cisco or asterisk, but these phone require a Ethernet connection they cannot be plugged into a home line. (They also require internet access to make calls and there is a little work involved in getting one running.).

SOURCE: Why can't I connect my corporate Cisco IP Phone

Connecting a hub or switch to the "PC" port on the back of the phone is not a recommended best practice by Cisco as the IP phone does not support spanning tree protocol.