persistance on sip traffic fails when the bye message comes

First of all, let's try and put this back into a single rule for clarity's sake. Second, let's add a little logic to make sure that we're trying to delete a persistence record that actually exists. Lastly, let's be sure we're using a valid persistence method to start with (uie rather than sip).

In the end, I think you'll end up with something close to:

when SIP_REQUEST {
  set method [string tolower [SIP::method] ]
  log local0.info "SIP Method is: $method"
  if { ($method equals "request") or ($method equals "invite") } { 
    persist uie [SIP::call_id] 
  } elseif { $method equals "bye" } { 
    if { [string length [persist lookup uie [SIP::call_id] node] ] > 0 } {
      persist delete uie [SIP::call_id] 
    }
  }
}

HTH,

Colin