Meeting an old friend....

After almost 4 years, we met again in the same place, where we said good bye last time.
Dont know how and dont know why we stopped calling each other for updates and then suddenly one day he saw a "look like me" girl in the MTR, he gave me a call. I was busy with other things so I didnt notice the call. When I tried to return call, no answer.
When i just let it be, I will lose a good friend like him forever. And that dont make me feel confortable...
So I messaged him today, then he called back. I missed again and I called back again. Finally we connected again.
He lost signel after he called me for the very first time so the system automatically transferred all the phone call to his office. And so he didnt know that i did call him back. He though that I have changed the phone number without informing him. And actually we still keep the phone# of each other even we have changed the phone for few times.