Can I call toll-free / 1-800 / 0120 numbers?

In most cases, no.

Toll-free routing varies by destination. Many toll-free ranges (US 1-800, Japan 0120, UK 0800, and similar) only accept calls placed from inside the same country and will reject international callers and calls through VoIP, like PuchiDen.

This is a restriction set by the toll-free number's owner, not by PuchiDen. On the other hand in most cases there are non toll-free versions of these numbers which you can connect to through PuchiDen.

For example, All Nippon Airways (ANA) Card Support Desk has two numbers:

• 0120-029-747 (Toll Free)
• +81-3-6741-6684 (For calls from overseas)

If a toll-free number is unreachable from outside its home country, the call simply will not connect, and unconnected calls are never charged.