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Unread 09-24-2007, 02:24 AM   #15
Join Date: May 2007
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Default Not only VoIP Sharing

Hi Martin,

I do not have a trace of a call from a PSTN access number in USA, but I can assure you that this issue happened not only in Brazil (VoIP Sharing), but also on a PSTN access number in Madrid, Spain (Adam Telefonia IP).

I must confess you that I do not understand which difference makes if the PSTN access number is either A or B. In my point of view this issue is related with an incompatibility of the type of NAT (Restricted, Port Restricted, Symmetric) and the implementation of the Loose Routing feature that causes the ACK message be delivered directly from that UA-Server to the UA-Client. Consequently, the source IP address of the ACK message is different (then unknown by the firewall) of the source IP address of the INVITE message that initiated the call setup. This is exactly what is happening since July. Do you agree with me?

As I said in another message, I guess you could clearly understand this issue if you made a test on a public network (typically in airport or hotel) with NAT type Restricted, Port Restricted or Symmetric.

Thank you once more.

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