The Saynoto0870 database contains one entry, an unverified one that contains 'Old Vic':
Ambassador Theatre Group 0870 0606624 0208 5447412 Donmar Warehouse, Old Vic, Duke of York's and other theatres
I then went looking for information on Ambassador Theatre Group (ATG) and found that its website is
http://www.theambassadors.com/The page that lists the theatres in the Group is
here. It says "ATG provides the ticketing service for the Old Vic Theatre", so I guess that means that the 0870 number goes through to the ATG offices, rather than the theatre itself.
ATG's
contact page lists two addresses:
London Theatres:
Ambassador Theatre Group Ltd
Duke of York's Theatre,
104 St Martin's Lane,
London WC2N 4BG
tel
020 7854 7000Head Office:
Ambassador Theatre Group Ltd
The Ambassadors,
Peacock Centre,
Woking,
Surrey GU21 6GQ
tel 01483 545800
The address of the theatre is:
The Old Vic
The Cut
London SE1 8NB
The number from the database, 0208 5447412, is an outer London one. Both the theatre and ATG's offices are located in 020 7 areas.
A search of 192.com for The Old Vic address reveals tel: 020 7928 2651 and fax: 020 7361 9161. These numbers are listed on the Old Vic's
contact page, but gives the 0870 for box office.
I suggest that you try the number I have highlighted for ATG's London office, which is based at Duke of York's theatre. You will probably have to ask to be put through as that number is probably a general/switchboard number.