I found an 01 number in 5 minutes without using sayno (I tried, you didn't have it)

My theory was this...A company would be unlikely to call its' other branches using the premium rate numbers (PRNs), would not turn 01 numbers into PRNs unless they were subject to lots of public calls, and like my firm would probably have an employee lookup accessable only to employees on their LAN.   So I looked up the firm on BT, found only PRNs at first because I limited it to the post code of the office I was dealing with.  When I left the location blank, BT said 'too many firms to list'.  Finally, I tried Midlands and was told to narrow it down to East or West Midlands.  Then I got 7 offices, two of which showed 01 numbers and got lucky on the first one, and it was a local call too.  I told the nice lady who answered that I had misplaced my contact's business card, gave her his name and which town his office was in.  After the sound of keys being worked rapidly she came back with the 01 number.  (I already posted it here)  
Superficial Watson!

I must be missing something of I have misunderstood your comment because I have tried to obtain alternative numbers as you have explained and it doesn't work for me

Can anybody else shed any light on the situation