Tricky Situation, need advice.

My father is now in a Nursing Home with NO Landline in his room. So his iPhone/cell phone is his lifeline to family. Without going into lots of family drama. One of my sisters was caring for him(we all took turns), got him a new cell phone number(I had been paying for his old one for 10+ years), and did not give the number out. Fast forward to him now being in the Nursing Home we were able to figure out his number. But the iPhone hasn’t been updated in so long it won’t hold a charge and is causing my dad issues. My sister won’t help him with any passwords for iCloud so I can’t help him. He doesn’t know if the contract is in his or her name, even though he pays for everything as she isn’t working and living off his money(for now).

my questions are:

I think I’m just going to buy him another iPhone for now. If the number isn’t the same, oh well, he can start calling people and tell them the new one. 
~Unless anyone has a better idea to find out how to check if I can bring his number over to my account and reset his iCloud passwords without any access to his emails, etc?

Re: Tricky Situation, need advice.
Customer Service Rep

We understand this is important for you, msampair. Our goal is for your father to have a working phone, especially for emergency situations. iCloud is a service provided by Apple and you can find additional information here: They can assist you with looking at the options to reset the password and gain access. 

In this situation, you can complete a transfer of service. This was you will assume ownership of this line and keep the number. You can find information on the Transfer of Service process here: Let us know if this information is helpful.