If I have Flight mode on will people know I'm abroad?

I have an Iphone 5s and want to take it on holiday, however, there are certain people I don't want to know I'm abroad.
If I turn Flight mode on would anyone phoning from the UK know I'm abroad?
If flight mode isn't on would they know? & how would they know? Thanks!

Added (1). I heard there was a different ringing tone when calling abroad?

When you turn n flight mode, your phone is basically an iPod. Nothing comes in or goes out. No one would know anything other than your phone was unreachable.

Airplane mode disables the wireless features of your iPhone, iPad, or iPod touch to comply with airline regulations.

When you enable airplane mode from the Settings screen, an airplane icon appears in the status bar at the top of the screen and the following wireless connections and services are turned off:

Cellular (voice and data)
Wi-Fi
Bluetooth
GPS
Location services

If allowed by the aircraft operator and applicable laws and regulations, you can re-enable Wi-Fi and Bluetooth while in airplane mode:

Wi-Fi: While airplane mode is on, tap Settings > Wi-Fi, then turn Wi-Fi on and choose a Wi-Fi network.
Bluetooth: While airplane mode is on, tap Settings > Bluetooth, then turn Bluetooth on.

Flight/Airplane mode cuts off the signal to your phone, so that calls and messages can't come in or out. It won't provide anyone with information about where you are.

They can't know where you are if your phone is not connected to the network.

When you connect, even with Wi-Fi, many programs broadcast your location.