HMR on Route header in INVITE

Hi

 

I am facing a case and need to use HMR to resolve. We noticed that somehow the Route header is stripped when passing through NN3820.

 

So. my question here is how we can prepare HMR such that when

1. if the Route header is presented, we will do some moification

2. if the Route header is not presented, we will add the Route header

 

Or, Can we

1. no matter Route header is presetned or not, strip it and then prepare a new one ourselves.

 

we have tried to add the Route header, but failed. can share the configuration for refernce?