I occasionally receive an incoming call on my Panasonic landline that shows nothing in call display but "Incoming Call". I don't ever answer and the call eventually disappears without ever being subsequently registered by my phone as a missed call. Just before the call drops the phone quickly flashes a "line in use" message. Normally the phone shows "Incoming Call" for a second and then having learned the number involved, flashes that number or say a province name.
Anybody have an idea what these peculiar calls are doing - beyond that they are spam?
By "free fax number" do you mean you have a second, smart ring, number associated with your landline?
Do you have a fax machine sharing the landline?
If you call the fax number, does the Panasonic phone behave as you describe?
Can you try the star code to find out the last number that called you and see what it says?
Make sure not to use the call trace one unless you want it reported to the police.
As recommended, I initially tried *69 to get the mysterious incoming call's actual number but the feature wasn't working. Telus chat couldn't resolve THAT issue. I subsequently tried picking up on one of the calls but all I heard was a dial tone.
Yesterday, after many months, I tried *69 again and it was working. The call according to this was from 1-604-555-1212. A discussion of this number on site WhoCalledMe.com showed that it's someone trying to get you to phone back. When you do, you are somehow automatically routed to 411 directory assistance and end up charged a small fee for the effort by your phone company. I'm not sure whether this is just a prank or somehow a money making scam.
The story behind 555-1212.
In the days of 7 digit dialing, 555-1212 was the same as dialing 411 for Directory Assistance and 1-604-555-1212 provided the capability for people outside of the 604 area code to call directory assistance for the 604 area code (BC TEL/TELUS operators).
If you see this number appear on your call display it is because it is being "spoofed" by a junk caller.
I think it is a quirk of Panasonic cordless phones. I have seen that happen over the years and there is some Caller ID information on my corded Nortel Vista phone but not on the panasonic. I can't be certain but that is the best explanation I have.