Which services will work overseas without an international roaming pack?

Without an international roaming pack, you won’t be able to use data unless connected to a WiFi network or receive or make any calls. You will, however, still be able to receive texts in any country that has an available mobile network for where you are (it doesn’t need to be an approved roaming country), but you won’t be able to send a text message (unless it's an iMessage on your iOS device and you are connected to WiFi).

For your safety when travelling, without a roaming pack, you can also call 112 in an emergency anywhere with a mobile network and this will route to the local emergency service – again, you will be able to do this even in a country that’s not an approved roaming country as long as there is an available mobile network where you are.