Hi, I am trying to use negative match in regular expression but without using !uri=~. For example, any uri not starting with 9. I tried this, if (uri=~"^sip:(?!9).*@testdomain.com") I got this error. ERROR: fix_expr : bad re "^sip:(?!9).*@testdomain.com" Does ser support this kind of regular expression? Thanks, Richard