I don't give my SS to anyone except the bank and for SS tax purposes. My last power company tried to insist I give it to them, when I asked WTF they needed this for simply connecting power they said for a 'credit check'. I talked further and found out they'd take a deposit in lieu of this and that's the road I took. I got the deposit refunded about 6mos later I think.
These companies really don't need it. When I setup my cable, electric etc. I didn't have an SSN, it takes time to get one when you are an immigrant. As soon as they learned I just didn't have one then they went down an alternate procedure. I think in the end I only had to leave a deposit with the cell phone company, everyone else just connected me.
This can be a pain down the line when trying to deal with these companies over the phone though as everyone wants the last 4 digits of your social as part of their authentication process.