Opal Court at Leicester is 0870 836xxxx = 0116 214xxxx

Both these prefixes are allocated to Affiniti Integrated Solutions.

0870 252 is also Affiniti, change date 09/2003

Within Liverpool (0151) code, Affiniti have the following prefixes (change dates shown after prefixes):

0151 122 09/2002
0151 515 04/1999

The first is a national dialling only number which means you must dial 0151 code, even when calling from a landline with an 0151 number. However, BT does not always connect to these numbers. It has been reported on here that NTL (Virgin Media) and Orange Mobiles can call these numbers. I suggest you try the second one first. If Leicester's is anything to go by, then it may be 0151 ??? + last four digits of 0870 number.

Please let us know how you get on. This will be of use to others who want to know the numbers.

I still believe that your room number will begin with one of the Affiniti prefixes I mentioned: 0151 515 or 0151 122.

Have I got it right that 0870 252 3789 is extension 789 ?

That is, the last 3 digits of the 0870 are the same as the extension number.

A Google of "0151 515" reveals quite a few numbers of the form 0151 5153xxx are in use. These appear to be large office complexes, namely Silkhouse Court, Tithebarn Street, Liverpool, L2 2LZ.

There is a page on the website for Opal which shows they have three buildings in Liverpool. See here.

Opal Court has 517 rooms and Aigburth Park has 470. There is no mention of how many flats are in Great Newton Hall. All have telephones in rooms, so I expect it to be the same system and therefore part of the same numbering scheme. So with Opal and Aigburth alone there are nearly 1000 numbers.

What they may have done is kept the last 3 digits of the 0151 the same, but changed the 4th from the end (maybe because those numbers are already in use, as we've found out). So try substituting it with 0 to 9:

0151 5150xxx
0151 5151xxx
[...]
0151 5158xxx
0151 5159xxx

When you make a call from the phone, does it give any number or is it withheld/private? If it is, try prefixing the outside number with 1470 and see if it gives a number on the receiver's caller display. I suggest you try ringing your mobile with and without 1470 before the mobile number. If you need to dial a prefix to get an outside line such as 9, then dial 1470 after this prefix, but before 077.... .

1470 usually works the opposite of 141. That is 141 withholds your number and 1470 gives it out (if it's normally withheld). Don't be surprised if it doesn't work though.