[OpenSER-Users] parallel forking

Dear All: I have found there are some devices can't process two 180 ringing after use OPENSER to do parallel forking, so, i have a idea that is used OPENSER to delete To tag in the To header before relay it , and it works well with eyebeam. But i can't find any spec to support my idea because it is against "early dialog" prograss and my question is how does UE(eyebeam or some client) to create dialog if there is no any To tag in 180 ringing but 200 OK has in the latter ? i think the UA will generate local ring tone but no any dialog after receives 180 ringing with no To tag? is it right ? thanks, allan DISCLAIMER: Sample Disclaimer added in a VBScript.