Cisco IP Phone 7940/7960
From VoIP.ms Wiki
Note: These devices need to have the latest firmware in order to have the SIP Configuration options mentioned on this article. For more details please contact your Cisco Service or review the following links:
- Press **# to unlock the Configuration Protection
- Some firmware versions must be unlocked by pressing the "Settings" button, scrolling down to the "Unlock Phone" option and pressing the "Select" softkey
- Press Settings button
- Go to "Network Configuration" to set the IP connectivity
- Go to SIP Configuration
- Select "Line 1"
- In Name and Authentication Name enter your VoIP.ms username(e.g. 100000)
- Enter your VoIP.ms password
- Enter any of the VoIP.ms servers (e.g. atlanta.voip.ms) as Proxy Address
- Configure Preferred Codec to g711u
- In Settings > SIP Configuration > Register Expires (You need to set a timeout < 3600s, please put 180)
- In Settings > SIP Configuration > Register with Proxy set this to YES
- Press Back
- Press Save to apply changes.
As an additional recommendation, Set "NAT enabled" to Yes, and on the "NAT address" parameter, enter the External (publicly addressable) IP address of Router or firewall, if any.
Important: Please make sure your timer_register_expires is set to 180 seconds. Lowering the setting to 180 seconds refreshes the SIP invite and creates a new dynamic route every 180 secs. The option is also available directly on the phone menu through: Settings -> SIP Configuration -> Register Expires
Using the Cisco SIP IP Phone Menu Interface
Cisco SIP IP Phone 7960 Administrator Guide 
- You can check the most commonly used Star Codes from Cisco/Linksys Star Codes