engaged tone when I call NTL (516) telephone numbers from my landline

[#1]

my phone is working perfectly for all other numbers.  I can make and receive calls but when I call any number beginning with 0208516 I hear the engaged tone.  This has been happening for about 2 months (but was working fine before that).

I am aware that these numbers were given out in the 90s by a telephone company called NTL so I am wondering if there is some sort of block on them preventing me from being connected.  

  I have been reporting the fault with Plusnet for over a month and my daughter (who's number it is) has had her line checked but it is still happening.  Plusnet sent out an engineer who couldn't find a fault. then they seemed to have fixed the problem a week ago but now it has happened again!

has anyone experienced this or does anyone have any idea what could be wrong.  Any suggestions gratefully received!

[#2]

Hi @rmdavies,

I'm really sorry to see you're having issues calling specific numbers.

I'd like to raise what we call an Interconnect Network Fault. Could you reply to the ticket I've raised Here with the following information? My colleague @SammyM will then follow things up with you as today is my last day here. 

• A list of the phone numbers where you hear an engaged tone when ringing.
• When did the fault first happen? Specific date / time if possible, though approximate if not.
• Does the fault only happen at a certain time of day? Does it affect all calls or a specific percentage?

We may need more info but that should be enough to begin investigating for you!