said by vox357 :I already have a modem (Motorola SB5101U Surfboard) and I just joined CenturyLink. They have a list of compatible modems and the Motorola wasn't on it. Does anyone know if it really won't work?
The Motorola Surfboard series of modems is DOCSIS (cable Internet); with that model possibly being obsolete D1.1, D2.0 at best. CenturyLink offers VDSL, ADSL2+, and probably, in some areas, obsolete ADSL.
You can't use a DOCSIS modem on a DSL service. And if you ever go back to DOCSIS (cable Internet) service, you will probably find your SB5101U won't work well, if at all, on a DOCSIS plant. It is time to deliver it to either electronic recycle, or some museum somewhere, if they will have it.