Have you noticed recently an increase in the volume of calls made to your phone number by international callers you don't know nothing about? As for myself, I've been receiving dozens of calls a day over 2 weeks coming from indian numbers I had zero business with. I've been blocking each and every one of them but since they were always coming from a different number, I felt somewhat powerless. I could not tell you what they wanted from me as I haven't answered not even one of them and have deleted their voicemails as they appeared without even listening to them.
While complaining about this with some of my colleagues, I've been made aware that there was a huge hack at Instagram recently and that thousands of users' accounts were compromised and their personal info (including phone numbers) was now in the hands of malicious hackers! I can't tell you for certain that that's what happened to you, but I can certainly help you avoid that faith to your phone number in the future.
It's in fact quite simple, all you need to do is download a third-party texting app - as for myself, I use TextMe - you then get to choose a local phone number and here's the trick: everytime that an app (like Instagram, Facebook, Gmail...) asks for your phone number to send a verification code, instead of giving away your real Fido phone number, simply use the number given by the app. That way the next time Instagram is hacked, your Fido phone number will still be safe and you won't find yourself audibly sighing at your phone ten thousand times a day.
If you're experiencing a high volume of unsollicited calls right now, hang in there! For me it lasted about 2 weeks and then it was all over. I guess they got tired of hearing my stupid voicemail. Good luck!