Hi. Reading Gettingstarted04.pdf at 1.6.2 from Onsip.org, seems to me that I _always_ need a rtp relay when both UA are nated. Because NAT will not be able to know what ports must be forwarded to the internal UA. Is this true? Is there any scenario where I can have both UA nated and they can just use SIP signaling with ser, and stablish the RTP flow between them? Thanks in advance, Sebastian.