Once. It was a massive mistake.
You'll end up finding your way through their script quickly and they'll ask for your personal details to provide further assistance by the end. If you can keep your number private then do so, otherwise they could legally locate you within an hour as an emergency if they can prove you said you fully intend to exit on the call.
The numbers are not any REAL help if such a thing does exist, they're a very low cost distraction for them to operate, and a conversation always has a possibility of being a very stimulating distraction. So it boils down to whether you really just want someone to rant to, in which case it would be helpful to you. For me I would consider that to be just fooling myself.