witheld number blocked

[lorraine29]

I am currently ex-directory with the option to withold my number, I am wanting to ring my boss but as she has the option to barr all witheld numbers I can't get through, I know there is a number I could use as a prefix which would reveal my number so i can get through but i'm not sure what it is, can anybody help

[Ethel]

If you use BT it is 1470

[lorraine29]

thank you, thats great

[CathH]

When I ring withheld numbers from work, instead of dialling 9 for a line (a very large switchboard) I have to dial
10 then 1470 then the number