Is it true that old mobile phone companies are soon to cut off their service to older phones?

I am told that older mobile phones will soon become useless in the UK, because the phone companies are going to stop giving service to these “old timers”.
I have two new phones, but have kept my old phone (about six years or so old) as a backup, in case one of the modern phones breaks down.
The old pay-as-you-go phone still has a fair amount of credit on it, so I also use it for unimportant text messages. My intention was to keep using the old phone until the credit ran out, and then hand it over to one of the phone recycling agencies.
But, if what I am told is true, the phone will become useless in a short time.
Can anyone please tell me what types of phones are to be compulsorily phased out, and when this will take effect?

yes its true. because you cant update the phones system or roam or 911 track them. call your cell company and ask them what phones and when they are going to do this.

Recycle Your Mobile Phone for CASH!!