Call forwarding problem...

A number comes up on my caller ID on my land line at home. It is
accompanied by a message from an unnamed caller. The message sounds
official and it states that this is not an advertisement but the call
is of an urgent nature.
I return the call using my cellphone. When the call is made, I get the
sound that used to accompany the dropping of a dime into a pay phone
before you dial. The call ends abruptly and, after that, all calls are
forwarded to the number from the caller ID and message. If I call the
number during regular business hours, it gives the same obscure message
except it thanks you for your call but gives no information about the
company name, etc.
I called my cell phone carrier and got a serious runaround. No one
could or would explain why this happens. I ask to be forwarded to their
tech support people and the answers I get are ridiculous explanations
and they suggest I cancel my call forwarding which is part of my plan
and I do use occasionally. The 'tech support' deny some obvious
capabilities of DTMF tones.
Does anyone have any ideas or experience with this situation?
Thank you.