Perhaps this may be a better solution:
have a friend make a tape recording explaining your situation such as:
My name is David, I am deaf and I cannot hear you. I am in need of emergency assistance, my address is 12345 Rosebud Lane. My phone number is 555-1234.
When you need assistance - dial 911 then put the receiver over the speaker of the tape player. Leave it there until assistance arrives.
This is an excellant idea! Good thinking!