Or buy an international sim card in the UK before you go.

或者在离开之前在英国买一个国际手机卡sim。

youdao

If you travel to Canada and want cellular service for more than emergency use, then plan on purchasing a local SIM card and perhaps using Telestial or another International virtual GSM network provider for inbound service.

FORBES: How to Save Money on Mobile While Traveling in Canada

Visitors can now buy a SIM card at the airport, which will let them make international calls.

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However, once you leave the country where you bought the local SIM card, the calls you receive from there will rack up international roaming charges.

CNN: Navigating cell phone headaches overseas