Hi Per, This is a tough problem. There are indeed situations when you are stuck behind a NAT over which you have no administrative control, e.g. in a hotel, or at a vendor or customer site. Although there is generally no signaling problem on outgoing calls, especially if you use fast start and/or H.245 tunneling, a NAT that is unaware of H.323 has a potential problem with the incoming audio: 1) The NAT doesn't know what host to send it to, until it sees some outgoing audio from that host. 2) Most calling phones / gateways don't send audio until CONNECT is received. 3) If the destination is the PSTN via a commercial ITSP, you won't get CONNECT until the call is answered. This means that you will not be able to hear announcements such as "the number has been changed ..." or "the party you are calling is out of range". Depending on the carrier, you may not hear audible ringing or busy signals, either. There is usually no trouble if the destination is an IP phone, an ATA, or a gateway with analog POTS lines. It is often necessary to set ProxyForNAT for reliable operation without DMZ. Unfortunately, that generally carries a penalty in voice quality and/or delay. --Stewart ----- Original Message ----- From: "Per Kreipke" <per@xxxxxxxxx> To: <openh323gk-users@xxxxxxxxxxxxxxxxxxxxx> Sent: Tuesday, July 06, 2004 3:17 PM Subject: RE: Question about NATed endpoints > Stewart, > > Thanks, very informative. > > I'm curious, if only making outbound calls, is the situation the same? E.g. > is it necessary to put the gateway in the DMZ/open ports? > > Thanks, > Per ------------------------------------------------------- This SF.Net email sponsored by Black Hat Briefings & Training. Attend Black Hat Briefings & Training, Las Vegas July 24-29 - digital self defense, top technical experts, no vendor pitches, unmatched networking opportunities. Visit www.blackhat.com _______________________________________________________ List: Openh323gk-users@xxxxxxxxxxxxxxxxxxxxx Archive: http://sourceforge.net/mailarchive/forum.php?forum_id=8549 Homepage: http://www.gnugk.org/
