[reSIProcate] Editing Contact field and finding Registrar

[Yong, Chee Yeew]

Hello,

I am trying to use DUM's makeRegistration to send a REGISTER request to a
SER machine connected through a LAN.

I have 2 questions (beginner's questions, really):
1) How do I edit the Contact header field using DUM? Or do I have to use the
reSiprocate methods instead? 

2) In the SIP standard, it states that the registrar address (not URI,
presumably) should be obtained via configuration. However, I am not sure how
to go about getting the REGISTER request to be sent to my registrar (the SER
machine). Do I specify an IP address? How will I be able to do this?

Hopefully this is not wayyyy too basic a question (or two). 

Thanks.

Chee