DSL Modems: Aren’t they all the same?

Question for any tech-minded readers out there: I’m trying to sign up w/Qwest for DSL service at our new house. We had DSL w/Verizon at our old place so I still have the DSL modem that Verizon made us rent/buy. Qwest tells me I have to have one of the modems on their list of compatible modems, but I don’t want to buy another modem. Are they right that if I don’t have one of the modems on their list the service is not going to work? Could Qwest-provided DSL really be so different from Verizon-provided DSL that they require different modems? I mean, I’m sure it’s possible, but I’m skeptical. Anyone know?