No, if you block your CLI it will show as a 'private' call and the receiving party cannot tell where the call is coming from. That would be the norm for many calls from overseas, although I do notice that here in the USA, calls from Europe increasingly show the CLI as +442701231234, for example. Calls from some other countries eg Australia just show 'private'. It all depends on the CLI system that is in use - they do vary between countries.
However, bottom line, apart from the nerdy stuff - if you block your CLI, they will have to assume it is an overseas call (and if they ask, lie
)