Nextel in the USA offered that as well. A number of carriers also have marketed "first minute free" on incoming, so that you could always hang up in the first minute and avoid charges for calls you did not want.

When they do free incoming, they run the risk that some customers will call people and say "call me back" to avoid billing lots of minutes.

Today 800 numbers are so cheap you could offer call-me-back on my 800 number affordably.