The main number for a clinic will take you to the front desk staff, from whom you can obtain the direct contact of the appropriate provider.
Suggested script:
"Hi, my name is [insert name]. I am a [provider role] with San Francisco Unified School District and I am requesting to speak to [insert UCSF provider role] in order to gain more information on a student that we serve together. May I please be transferred to speak to them, or can you provide direct contact information for them?"
If the SFUSD provider that you are communicating or sharing information with is a clinical provider (i.e., nurse, PT, OT, SLP, audiologist, social worker or physician), an ROI is not needed for direct communication about evaluation and treatment of the child.
If the SFUSD provider is not a clinical provider (i.e., teacher or administrator), an ROI is needed.
See here for corroboration and details on hhs.gov.