(Facebook / Newshub.)

According to reports from people who received the calls, usually the caller will hang up as soon as they answer. Those who have managed to establish a conversation say the caller purports to be from a finance company.

Spark and Vodafone both told Newshub they had received a spike in reports about calls from Canada from concerned customers.

"We've received reports from a number of customers who've recently received calls from numbers beginning with +1647, where the caller simply hangs up once the call is answered," a Vodafone spokesperson told Newshub.

Similarly, Spark said "there [have] been a few reported calls purporting to originate from Toronto."

The advice from both companies was simple: Don't give away any personal information, and don't call them back.

The reason for this is that a return call could result in international charges being placed on your account.

Both companies advised worried customers to follow the advice for dealing with unwanted calls which is provided on their websites.

Newshub.