Short dial Script

Hi,

I am trying to configure a script for short dials.  On our previous asterisk box we did the following

insert into extensions (context,exten,priority,app,appdata) values ('clinton','71xxxx','1','Dial','SIP/71xxxx01&SIP/71xxxx02');

I am trying to do this in a more simple way rather than having to configure each site as above (theres about 400 of them).

I have a script of the following which works fine if both phones are regestered at the site.  But if one phone is disconnected for any reason the call does not hit the other.

exten => s,1,Verbose(Clinton Cards Inter site Call)
exten => s,n,ExecIf($[${MACRO_EXTEN:0:2} = 71]?Dial(SIP/${MACRO_EXTEN}01${TL_DASH}${tenant}&SIP/${MACRO_EXTEN}02${TL_DASH}${tenant}))
exten => s,n,ExecIf($[${MACRO_EXTEN:0:2} = 81]?Dial(SIP/${MACRO_EXTEN}01${TL_DASH}${tenant}&SIP/${MACRO_EXTEN}02${TL_DASH}${tenant}))
exten => s,n,Dial(SIP/${MACRO_EXTEN}${TL_DASH}${tenant})

Any help would be much appreciated.

Thanks,

Huw