Grandstream Dial Plan

[karlrosch]

I know this isnt a 3cx question but maybe someone is an expert on grandstream

I have a grandstrean gxw4104 gateway

I need a dialplan that will replace a lead 9 with * any thing else it must
leave untouched

I tried {<9=*>x+}

This works fine for numbers with a leading 9 but other numbers wont dial