For those that need their connectivity, there are a few ways to starve the inner mobile beast of unmanaged data usage and stay connected whilst traveling with your smartphone.
Do what I do and there is no data sucking vampire lurking and no surprises waiting at home, apart from your lonely smartphone that has had a holiday because it was turned off.
Can't leave your lifeline behind? Pull out the sim card and use it with a local sim card. Just remember to advise your carrier before doing this so they are able to unlock your phone if necessary and don’t forget where you put your sim card at home.
If you insist on traveling with your smartphone intact, take a deep breath and turn off all data roaming. Pray that the ghost within will not magically reconnect to some random data slut unbeknownst to you. Then you can simply rely on the local free Wi-Fi. Make sure that the "free" Wi-Fi is secure by the use of a password; otherwise you are leaving yourself open to hackers. Remember to backup your files, emails and photographs on an independent external hard drive safely tucked away in a cupboard at your house. Use a free password manager to protect your online identity. Above all, don't lose it!
Turn off any function on your smartphone that uses location or GPS, such as Google maps. Be prepared, you know where you are going, download any maps you think you may need before you put a foot in the airport of your departure. Or simply ask for directions, you have a tongue in your head. If you don't speak the local lingo, gesticulate with those beautifully manicured hands, or simply go to an internet cafe. No internet cafe anywhere? Yes, this does happen in some out of the way places. Compound this with no understanding of the local language and you are obviously in the back of beyond where no sane person would travel. If this is the case, you must be the adventurous type who should thrive on the challenge of not knowing how to get to where you want to go. There is no rush; it is supposed to be a holiday. I have experienced some of the best sight seeing trips by not getting to where I wanted to go in the first place.
Before you jump the plane, have a look at some social apps such as "WhatsApp" or "Viber" which both offer a different way of keeping connected using Wi-Fi.
Another way to circumvent the gremlin, would be to invest in a dual sim phone. One local sim card for outgoing calls, and your "at home" sim card for receiving important incoming calls, both on the same phone.
Or, be super-cool, relaxed and stay connected with a global SIM Card that covers multiple countries! An international mobile service for smart travellers who want to stay connected. Some global services even have the added benefit of adding a second number for your country of origin and have reasonable data plans. Mmmm, now that even interests me. One sim card and great rates, it is getting even harder not to stay connected.