Same problem here. Was first aware of unavailable telephone service approx. 23 hours ago. Did, after 2 ineffective calls to Comcast agent, finally try resetting modem, and got the same "you're not connected to a supported device" message. (Am renting an Arris cable modem from Comcast.) Each agent promised a callback from a technical expert, but so far, nothing.
There seems to be little point to scheduling a visit from a technician. This is a problem affecting multiple users in different locations. That indicates a problem in the system, emanating from a central office, not an individual residence.
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