Snom 4S Manuale Utente

snom technology AG • 15

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S N O M

4 S N A T F

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2.3 SBC Behaviour

2.3.1 Registering

When a user agent registers, it puts its IP address in the top

Via. If the user agent is on public Internet or properly supports NAT, this

Via will match the perceived IP address. In this case the SBC does not

interfere with the registering process and just forwards this packet to the

registrar.

If the top Via does not contain the perceived address, the SBC

will take care of the request. It will replace the provided contact with a

locally generated contact and forward the request to the registrar (see

below).

Via: SIP/2.0/UDP 203.145.183.113:12975;branch=z9hG4bK-

abx3au3mxb01;rport

From: <sip:denny@snomag.de>;tag=k9p6fmeg7h

To: <sip:denny@snomag.de>

Call-ID: 3c26701d7cb9-pady07b5783t@203-145-183-113

CSeq: 14 REGISTER

Max-Forwards: 70

Contact: <sip:denny@203.145.183.113:12975;line=lhynyb3y>;q=1.0

Supported: gruu

Expires: 86400

Content-Length: 0
REGISTER sip:snomag.de SIP/2.0

Via: SIP/2.0/UDP 217.115.141.99:5082;branch=z9hG4bK-e8d1feb8138c3d85

0637ced821ef40a3;ua=c9b140ab598290e5bb491e9c3aaca440

Via: SIP/2.0/UDP 203.145.183.113:12975;branch=z9hG4bK-

abx3au3mxb01;rport=17401