A couple of questions:
1) What's the model number of the Belkin product that you are using?
2) Firmware version of the product as well?
3) Brand and model # of wireless adapter?
A couple of things to consider first:
1) You may want to try a different firmware version of the router first. Take a look at Belkin's site and see if they have any updated firmware versions from the one you are on.
2) After upgrading the firmware version on the box, try and set it on a different channel. Since 2.4GHz phones hardly tell you which channel they are working on these days, you can still release your network adapter from your own network and look to see what wireless devices are in your broadcast range of your box from the wireless adapters connection utility (whatever it may be). Make sure that you don't have any other devices in your range on the same channel, or simply put....just try a differnt channel on your own router for a while and try to rediscover the same problem on a different channel.
But most certainly reply in here with your model number because there are a couple of Belkin firmware versions for certain models that you want to stay away from. Hopefully the above will at least get you started though.