By the way, should I buy a phone card before leaving home or buy one in Barcelona ?
3 Answers
It's recommended to buy a SIM card before departure, which is cheap, and you will need a local Spanish number for others to contact you. I bought two orange cards and made free calls between them.
Buy it on Taobao before leaving, it's cheap and practical. Just search for "European phone card".
International roaming is 30 yuan a day with no upper limit. You can also buy it in Spain.