Sadly the consulate website simply states you can't enter with a cellphone and will need to "make arrangements" to stash your phone. Does anybody know if there is a nearby locker to put my phone in?
The German consulate in Boston has the same rule, which is rather impractical. So far I've been able to negotiate my way around it: Leave it at security or show them that it's turned off. Sometimes, they don't even ask.
Maybe you can call the consulate and ask. People on the phone tend to be more accommodating then websites.
There is not a service provided by the Consulate in São Paulo for this. On the other hand, there is a bunch of people providing these services around the Consulate. It is important to say that normally is people that leave around there or small stores. It is not 100% safe, but also, I never heard any problem.
Another option is to use a locker at the airport or bus station. If you will be in a hotel, you also can use their locker.