If someone is diagnosed with severe epilepsy do you call 911 every time they have a seizure?

I work in the mental health field and I have a client whose boyfriend has epiepsy. Sometimes he has seizures while I am there and I call 911 eveytime. Someone at work said that if they are diagnosed with epilepsy you do not need to call 911 when they have a seizure. I think I should call everytime what do you think?
My client is the girlfriend she does not have epilepsy.
I am a mental health tech. I am trained in CPR and first aid but I am also only trained to take care of mental health clients not ones with epilepsy.