grep by limit search

Shell Programming and Scripting
1

Hi
I am in new in unix,can any one tell how to grep the data by limit.
suppose I have below data:-

is :[1249]mSecs
is :[585]mSecs
is :[160]mSecs
is :[50]mSecs

requirement is how to grep the data which is having count greater than 1000 msecs only.

thanks in adnavce.

2 
$ echo "is :[1249]mSecs
is :[585]mSecs
is :[160]mSecs
is :[50]mSecs" | awk -F"[][]" '$2>1000{print}'
is :[1249]mSecs


awk -F"[][]" '$2>1000{print}' inputfile
3 
grep '\[[0-9]\{4\}' infile