Internet disconects when phone is picked up

Hello,my problem differs from the rest like it.. my internet remains fine on my computer when the wireless phone is picked up but on my xbox 360 and my psp i instantly get disconnected till the phone is hung up..which is ticking me off because im either on skype talking to my girlfriend or gaming online (things i dont want interrupted)
Heres where it started I have a Ambit u10c018.80 Modem, in which ive tried to change things on bvut cannot..theres only refresh page options, and i have a Net gear wireless N router in which i went into the routers wireless settings and changed it to accept B/G only because the PSP supports G and not N, Ive Tried changing all the connections but none of them work on the PSP except the one i recently changed it to where the phone being picked up and answered make me disconnect on both psp and xbox 360. before this when i only used my xbox and had different settings i was fine. How do i fix this? do i really have to get a splitter? They seem expensive and dumb. Please help soon! thanks!