It's a scam.
I used this service as a professional, not as a client. In just a week I was charged 150$for clients who supposedly had clicked on my telephone number. I asked customer service about this practice and replied with
"If you receive a message from the customer,
If the customer consults your phone number to contact you,
If you consult the customer's phone number,
If you use the platform manually, when the customer has not contacted any professional, we send his number to the professional who sent his quote first.
These coordinates are invoiced."
Basically, StarOfService will charge the professionals at their will.
Beware of this scam!