I say no, it's not safe for the reason you mention.
In a home where you can locate and verify the wiring from your premises to the telco interface are physically disconnected clearly yes you are safe to do this.
Condos and multi-unit apartments are not so black and white. Who knows where the disconnection is made (should be at a Network Interface, see
here for more details), or even if it's made physically, or maybe it was done at the Telco central office or somewhere else along the wiring pathway.
Save yourself the trouble of having issues when some storm or technician shorts out the wiring somewhere along the line and out of your control, and use a cordless phone (or phones) to get dial tone in your living space. That same question comes up on here occasionally and the above is the collective best approach.