Theres a lot of way to have a communication with someone, If your service provider is not open in roaming you can call each other using a social media account like facebook messenger its free international. Or go to your nearest sim card provider to make open line your number so you can call to the other country.

You should be able to use WhatsApp or Skype for this purpose as long as you have a Wifi connection on your smart phone.

Another option is to create a free meeting through https://meet.google.com/ and have each party call in using the dial-in number.

Greetings,

You can ask the person to download the whatsapp application from playstore, take his/her phone number and call on it. I'm a business coach based in India, I usually have my calls with clients on WhatsApp. Let me know if I can be of any other help. I can be reached via my clarity link on my profile here om clarity.

Best of luck.