The most important thing to remember about these new regulations is that they only apply at "certain overseas airports".
In general, the TSA has no authority at overseas airports, and all airport security is carried out by the equivalent security group in the country the airport resides in.
However at some international airports, direct flights to the US do undergo additional screening, which generally consists of little more than a few basic questions, a (normally rudimentary) searching of your bags, and if you are "randomly" selected, a metal detector wand and/or pat-down search of your body - although the exact process varies from country to country and person to person.
What was announced recently was an additional check in this process, which will most likely be applied "randomly" (for some definition of randomly that probably isn't), and probably only to a small percentage of travelers.
According to the TSA Blog :
Electronic devices are already screened daily, but now, security
officers might ask that you power up your devices, including cell
phones. Powerless devices will not be permitted onboard the aircraft,
so it’s important to have them charged prior to going through
There is no mention of actually having to use the device (eg, make a call) in either the TSA blog or any other reference to these requirements that I've seen. As long as your device can be powered on (or, obviously, is already powered on) then you're good!
So realistically this new check will really only impact you if you fly out of certain foreign airports on a flight to the US, AND you're selected for additional screening, AND you have an electronic device that is turned off, AND if you're not able to turn it on for some reason.