Oh dear that’s not a good start to your hosting experience.
I think you were right to turn down all three. In your situation I would be tempted to give Airbnb a call and explain your first three bookings have been suspicious and do they have any advice on what could be causing this. Tell them you are concerned it will affect your status and see what they say
(I wonder if perhaps you have your pricing too low? Don’t use Airbnb’s smart pricing as it normally bares no relation to the market. Look at what hosts with comparable properties locally are doing and follow their model).
I have noticed that in the last month or so, for some reason I people have been able to create a profile and book without uploading a photo, which is something new.
It’s certainly not normal for people to ask you to call them - this most likely means they are trying to either ask for a discount or want to go outside Airbnb to save on fees or both.
Here is a note that I sent to guests who book and don’t send the information I require.(happy for you to adapt for your own use).
"Thank you for choosing to stay in my home.
"In order to confirm your booking, please could you;
Upload a clear photo of yourself
Let people know a little about yourself and the guests who will be joining you.
Let me know why you chose my place
Let me know about plans for your stay
Let me know what time you are planning to arrive within my check in time of 6 - 11 p.m.
"I share my home, so I am sure you can appreciate it’s important for me to know something about people who will be sharing my home.
“I very much look forward to meeting you/meeting you both”.
I also ask for this information as part of my Instant Book requirements so that if they don’t provide it, then I have grounds for cancellation.