Welcome to the community!
I understand how worrying it can be to imagine your phone number has been hacked. However, I don't think that is what happened.
The spammers/scammers often use spoofed phone numbers when making their calls to prevent authorities from identifying who they really are. Sometimes they will use known phone numbers (ie CRA or RCMP or Police or a Bank, etc) to try to trick the recipient(s) into believing the calls originated from those sources. In other cases like your situation, they will choose random phone numbers to make those calls, often switching the phone numbers frequently. In some instances, the spammers/scammers will use the recipients' own phone numbers to make the calls. It's very unlikley they actually have access to your account.
All phone numbers -- whether landline or mobile -- are in databases which are readily available online. Certain prefixes are designated as landlines, others as Rogers, Fido, Bell, etc. Once the spammers/scammers have selected their target group, they choose how they want to spoof their number and have a computer sequentially dial the numbers of a desired area code/prefix combination from 0000 to 9999 and all of those customers would be with their desired target (see here).
The mobile providers have implemented Universal Call Blocking as a measure to try to reduce the amount of nuisance calls. In addition, a new technology, STIR/SHAKEN (Secure Telephone Identity Revisited/Signature-based Handling of Asserted Information Using Tokens) is being adopted to further reduce the amount of nuisance calls (see here). However, I have my doubts as to whether those measures will reduce the amount of SPAM calls. My understanding is the STIR/SHAKEN will only identify possible SPAM calls and mark the calls as suspected SPAM.
Hope this helps 😀
Thank you for the help.
I stopped recweiving those calls, but now I get calls from international numbers randomly during the day and night. It rings for a second or two and then disconnects auomatically. I got about 5-7 such calls in a day.
I keep blocking those numbers, but new ones come up. The screen shows that the numbers are from Fiji, Ascension Island, Tonga, USA etc.
It could be a fraud, not because someone got your number but because they got you to call them and when you place a call it can be to a paid number or they could start making up stories about your number being used for fraud and you being responsible for things that are not real.
My advice is not to return any calls and block unkown numbers.