irule for SIP forward

The SIP::header remove method takes one of these two forms:

  SIP::header remove
  SIP::header remove 

Thus, if you are attempting to remove a specific Route header, and there may be more than one, then the form you provide will unfortunately not work. You must iterate through the Route headers until you find the position of the header to remove. In 11.6, something like this might do it:

set required_value ""
for { set i 0 } { $i < [SIP::header count Route] } { incr i } {
    if { [SIP::header value Route $i] eq $required_value } {
        SIP::header remove Route $i
        break
    }
}

Before 11.6, this may do it:

set required_value ""
set i 0
while { 1 } {
    switch [SIP::header value Route $i] {
        "" { 
            break 
        }
        $required_value {
            SIP::header remove Route $i
            break
        }
    }
}

I'm not sure whether the SIP::header sub-commands start at 0 or start at 1. If they start at 1, you'd have to adjust the code. And, I'll have to admit that I've not tested this, so ... good luck :).