Cisco ip phone 7942

Hi Everyone,
I planning to start ccna voice. I bought 3 7942 sccp phone by mistake i had reset it 123456789*0# all. Now I don't know what to do next. Can I used it or not?Kindly share the steps. I have downloaded the zip file (firmware). Kindly share the steps. Thanks in advance.
I planning to start ccna voice. I bought 3 7942 sccp phone by mistake i had reset it 123456789*0# all. Now I don't know what to do next. Can I used it or not?Kindly share the steps. I have downloaded the zip file (firmware). Kindly share the steps. Thanks in advance.
Comments
CUCM SRND 9x/10, UCCX SRND 10x, QOS SRND, SIP Trunking Guide, anything contact center related
A good place to start is understand the IP phone bootup process. Here's a good starter doc covering everything from VLAN tagging to bootup sequence. https://supportforums.cisco.com/t5/collaboration-voice-and-video/ip-phone-boot-up-process/ta-p/3127965
Once you give that a read, start with the phone registration process next, https://supportforums.cisco.com/t5/collaboration-voice-and-video/ip-phone-sccp-amp-sip-phone-registration-process-with-cucm/ta-p/3109183
Finally, learn how to add a device to CUCM, https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/8_5_1/ccmcfg/bccm-851-cm/b08uspha.html