When MCI wouldn't give me more miles to re-enroll for another 6 months, I switched to Sprint. They gave me 10K for the first line and 2K for the second, plus 5 miles per dollar. There are other bonuses as well. They limk to 4 airlines, but not to my primary skymiles account. The best for me was Northwest. You certainly don't want to give MCI continued patronage for nothing. If you've never been an MCI customer, they have a good program. They have links to other airlines, including Delta. You can get 11K for signing up 2 phone lines.