What does this mean when you call someone?

[Anonymous]

So I have a friend from school that I stayed in contact with. He doesn't have social media so we keep in contact by SMS. Everytime we text he always says he is happy to hear from me but I rang him a few months ago and when I ring I just hear a beep and then then it says "The number you have called is not recognised". He has had the same number for 15 years so I dont know what coukd be happening. I called him on my friends phone and I got the same thing. What could this mean?

[Anonymous]

Sometimes the cell service just doesn't work and does that. I have that with my not-girlfriend a few times. It usually rectifies itself over time. We found we could text each other but not call for a while.

Also there are phone plans that are text only I believe. Usually used by businesses who are jerks and don't want customers actually calling them but want to give them a sense the business cares in a manor they can easily ignore.

[Billlewis]

Was it a cell number or a land line?

[Asker]

Cell number

[Billlewis]

Then he probably did change it, and it may have also been because of bill collectors, etc.

[Anonymous]

Phone cut off, changed the number etc.

[BarryLiverstone]

Ummm