If you are experiencing interfearance issues with your WiFi and 2.4Ghz cordless telephone (or other wireless consumer device) then before replacing your phone (or wireless device) with a model operating in a diffrent frequency, like a 5.8Ghz or DECT phone, you can try changing the channel that the WiFi router operates on. Normally this will reduce or eliminate interfearance issues.
To change the channel that your router operates on, you first must log into your router, which can normally be accomplished by entering http://192.168.1.1 into your web browser. If that is not the address for your wireless router, then you need to determine what the IP address of your wireless router is, to do this click the start button and type in CMD into the search bar. At the comand prompt enter IPCONFIG then hit enter - you want to see the default gateway IP address, and then enter that into your web browser.
Once you are on the web interface of your router, you will likely need to enter a user ID and password. Common combinations are admin/admin, admin/password, and admin/(blank). If none of these user ID/password combos work then you will need to check the user manual for your router, or google the default password for your brand and model router (sometimes this information is actually located on a sticker on the bottom of the router).
Once logged into the router web interface you need to look for the wireless settings, and change the channel number that the router operates on. Once you save these new settings you are done, you do not need to make any changes to the wireless devices that you have set up to connect to your router (unless you also change the SSID of the router, or the security settings).
If you are still having issues, you can attempt to change the channel again. There are several choices, and one should reduce or eliminate the interfearance. If you continue to have issues, you may need to replace your phone (or other wireless consumer devices) or use a wired network, and disable the wireless radio in your router (also located in the web interface settings).
When purchacing new telephones, or consumer electronics try to avoid purchacing devices that operate within 2.4Ghz. If you are purchacing wireless video cameras, or video senders it may be difficult to locate products that are not within the 2.4 Ghz range. In that instance you may want to consider replacing the router with a 802.11a router which operates within the 5Ghz range, however locating 802.11a hardware is difficult, since that standard did not really take off. Also, since 802.11a operates in a diffrent frequency than 802.11b/g/n it is not backwards compatible with the wireless cards located in your wireless PCs so you would also need to purchace new wireless cards for all of your wireless PCs...