Some are approaching this by once they have got the name doing a search on Google and then picking up the phone details from SERPS Position 1.
If this approach is followed .tel has an inbuilt advantage since it's phone numbers are held in a structured way on the page, unlike other TLDs.
Just tried out some "phone firstname lastname" searches (without the quotes) on my own .tel search engine http://www.net-link.com/tel to see if the first result (P1) that comes up contains that person's phone number.
Here are the results (in alphabetical order):
phone christopher vanderhorst - P1 http://personal.van.tel contains phone number
phone justin hayward - P1 http://justin.tel contains phone number
phone mark kolb - P1 http://mark-kolb.corporate.kprobe.tel contains phone number
phone mike seaton - P1 http://mikeseaton.tel contains phone number
So a small sample, but all returned P1 of SERPS with the phone number in, even though 2 of 4 did not have a phone number listed in the home page.
Check out your own .tel at http://www.net-link.com/tel and see if your .tel page containing your phone number comes up at SERPS P1 for "phone firstname lastname" (without the quotes) - it looks like this could be a prerequisite for Call By Voice working OK for you !