The number belongs to the Bariatric Surgery Registry, which is part of Monash University. If you have had weight loss surgery, and haven't "opted out", they are ringing to see how you are progressing to ensure the procedures are as effective as possible. They do this every year for up to 10 years.

I called back number (03) 9903 0982 spoke to a woman but did not hear her properly when she mentioned the company name.