Справочник Пользователя для SonicWALL 5.8.1

VoIP server returns phone B media IP information to phone A - Phone A now has 
enough information to begin exchanging media with Phone B. Phone A does not know that 
Phone B is behind a firewall, as it was given the public address of the firewall by the VoIP 
Server.

Phone A and phone B exchange audio/video/data through the VoIP server - Using the 
internal database, SonicOS ensures that media comes from only Phone A and is only using 
the specific media streams permitted by Phone B.

The following figure shows the sequence of events that occurs during a local VoIP call.

The following describes the sequence of events shown in the figure above:

Phones A and B register with VoIP server - The SonicWALL security appliance builds a 
database of the accessible IP phones behind it by monitoring the outgoing VoIP registration 
requests. SonicOS translates between the phones’ private IP addresses and the firewall’s 
public IP address. The VoIP server is unaware that the phones are behind a firewall. It 
associates the same IP address for both phones, but different port numbers.

Phone A initiates a call to phone B by sending a request to the VoIP server - Even 
though they are behind the same firewall, phone A does not know Phone B’s IP address. 
Phone A initiates a call to phone B using a phone number or alias. 

VoIP Server validates the call request and sends the request to phone B - The VoIP 
server sends the call request to the firewall’s public IP address.The firewall then determines 
phone B’s private IP address.

Phone B rings and is answered - When phone B is answered, the firewall translate its 
private IP information to use the firewall’s public IP address for messages to the VoIP 
server. 

VoIP Server returns phone B media IP information to phone A - Both the called and 
calling party information within the messages are translated by SonicOS back to the private 
addresses and ports for phone A and phone B. 

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3IGNALING

-EDIA