Rachna,
Please refer to Point No.2 (vii) of Notification No.6/2005-ST dated 01.03.2005, containing provisions relating to small service providers. The notification was last amended vide Notification No. 8/2008-ST, where basic exemption limit was increased to Rs.10 lacs. The Point No.2(vii) is as follows:
"2. The exemption contained in this notification shall apply subject to the following conditions, namely:-
(vii) where a taxable service provider provides one or more taxable services from one or more premises, the exemption under this notification shall apply to the aggregate value of all such taxable services and from all such premises and not separately for each premises or each services;"
Hence for the purpose of calculation of basic exemption, aggregate value of all taxable services, provided from all premises belongng to the assessee, shall be considered.
Hope this clarifies your doubt. The notification is attached below for ready reference.