Snom 4S manual Codec Control, Web Server Integration, Clir Addresses

[ S N O M 4 S N A T F I L T E R ]

packet. This setting does not only help you in making the packets shorter, it can also help you to keep some parts of the SIP message secret. For example, you might want to remove P-Asserted-Identity headers from all SIP messages, because you don’t want others to see which identities you already checked.

4.3.15Codec Control

In many environments, you want to exclude codecs from being used, although both communication partners could agree on them. The “Allow only the following codecs” setting lists the codecs (separated by space) that you will allow. If you don’t set anything here, all codecs will be allowed. The codecs must be written in their SDP name, for example “ulaw”, “alaw”, “gsm”, “g729”, “g723”, etc.

This feature can be used, for example, to make sure that only low-rate codecs are being used. The user agents might otherwise agree on ulaw, which might lead to breaking voice if the bandwidth is not suf- ficient for a stream using ulaw.

4.3.16Web Server Integration

The description of the web server integration follows in the next

chapter.

4.3.17CLIR Addresses

The SBC has the possibility to hide the identity of the caller (see description in the following chapter). For this feature it must decide when to hide the identity. If it hides the identity too early, the further processing in the data center will be difficult. Therefore it must make a decision when the request leaves the influence area of the data center.

When the request is sent to a UA that is handled by the NAT Filter, it does perform this step. However, when it is sent to a PSTN or IP-gate- way, it also must hide the identity. The setting Outbound Addresses (for CLIR) lists the IP addresses that also trigger a hiding of the identity. The format for this setting is the same as for the trusted IP addresses.

4.

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