03-9937-7700

Its just an outsourced contact centre used by Optus to handle thir relationship management with their clients. It is in no way suspicious. If you want to opt for a better mobile service plan then these guys that call you up can help you. They are based in Fiji.

My partner just got a call from (03) 9937 7715 which is another number from the same company.
They seem to be a legit marketing company however they refused to not record the call and it wasn't even an automated message notifying him of the call being recorded, but the woman making the call stated that fact.
They also wanted personal details as a confirmation even after he had stated he wished to terminate the call - so even if it is Optus it's very suspicious and i wouldn't pass on any details to them.
Conversations should not be recorded if the customer requests otherwise nor should they push for your date of birth or address after you have said you do not wish to continue the phone call.
Beware of scams that operate out of legitimate businesses.