my air exteme does not connect to my centurylink 660

My airport extreme will not connect to my centurylink 660 modem. I also have an ATT microcell connected. The configuration is from the modem to the microcell to the airport extreme. I can leave out the microcell and the airport extreme will still not connect. When I makes the changes in configuration I power every thing down and reboot. My sequence is to power up the computer, then power up the modem until all necessary lights are on, then power up the microcell until all lights on, then lastly power up the airport extreme. Centurytel says the modem/microcell are bridged and that airport extreme may have different addresses?? than the modem. I am not a computer person so all this is new to me. Any help would be appreciated.