Are your data fields numeric data type or are they character fields containing numbers?
Will the lengths of the numbers always be 7 in INTERVIEWED and 6 in SOURCE? If that is true you can try

CLOSE ALL
USE interviewed
INDEX ON MOD(fixed_line,1000000)  && For Numeric field
INDEX ON SUBSTR(fixed_line,2)     && For Character field


SELECT 0
USE source
SET RELATION TO fixed_line INTO interviewed
REPLACE ALL flag1 WITH interviewed.flag1 FOR FOUND('interviewed')

>hi all,
>
>i try to compare between 2 tables via field(fixed_line) at 2 tables
>
>but source.dbf have fixed_line as 7 numbers, and another table have fixed_line as 6 numbers,
>i need to to begin from second number from source.dbf
>
>as 8524163 begin form 524163.
>

>CLOSE all
>
>USE INTERVIEWED in 0
>INDEX on fixed_line TO ll
>USE source in 0
>INDEX on fixed_line TO hh
>
>
>
>replace IN source ;
>   FOR fixed_line==LOOKUP(INTERVIEWED.fixed_line,fixed_line,INTERVIEWED.fixed_line) AND NOT EOF('INTERVIEWED') ;
>   flag1 with INTERVIEWED.flag1
>

>thanks.