Doctor,please give me your cellphone number

Doctor, please give me your cellphone number.Then in case of an emergency we can contact you directly.
I receive such request very frequently. How should I respond?

You will think that this is a reasonable request. Each and every patient should be able to contact the treating doctor directly in an emergency. You wont have any second thoughts about how I should respond. But.............
I am sure if each and every patient I treat get my cellphone number, I wont have a single minute of peaceful living. I will be deluged with calls while sleeping, eating, bathing, driving, when seeing patients in my Consultation room, while taking rounds etc etc. Sense of propriety and ethics are forgotten. The facility will be misused [as some already do who have somehow got my cell number.]
I am available in the daytime at my land phone numbers. At night in case of an emergency, the patient have to approach the hospital were I work. The staff at the hospital can contact me 24 hours a day.

For some of my patients, I give my cellphone number without hesitation. They are
1. HIV positive persons
2. Type 1 diabetes patients
I don't hesitate for HIV positive persons, because I feel with all the stigma and discrimination they face, they should at least be positively discriminated by me. They should be able to talk to me anytime they want.
Type 1 diabetes patients need constant communication with the treating doctor as they have to self manage a lot and may need physician guidance in management.
Another reason for lack of hesitation is that 'positive' persons and type 1 diabetics under my care constitute less than 1 percentage of total number of patients. So, I need not loose sleep giving away cellphone numbers to them.
Do you think of me as a selfish and uncaring doc?