Asterisk modified src IP address in SDP? Is this normal?

Please help me identify the problem.
I have Asterisk and 2 zulty’s 2x2 on the LAN.

It looks like the Asterisk modified the IP address of the destination on the SDP. is this normal behaviour?
Setup consists of:
Asterisk IP add=

Ethertreal traces showed: (look atht e Src add and Dst Add where the src add is the IP of the asterisk?)

changing the Canreinvite does not affect any of the outcome.

Trace of Etherreal:

Frame 3 (766 bytes on wire, 766 bytes captured)
Ethernet II, Src: 00:30:48:12:43:9a, Dst: 00:0b:ea:80:51:66
Internet Protocol, Src Addr: (, Dst Addr: (
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
Total Length: 752
Identification: 0x0001 (1)
Flags: 0x04 (Don’t Fragment)
Fragment offset: 0
Time to live: 64
Protocol: UDP (0x11)
Header checksum: 0xb3a7 (correct)
Source: (
Destination: (
User Datagram Protocol, Src Port: 5060 (5060), Dst Port: 5060 (5060)
Source port: 5060 (5060)
Destination port: 5060 (5060)
Length: 732
Checksum: 0x125a (correct)
Session Initiation Protocol
Request-Line: INVITE sip:1001@ SIP/2.0
Message Header
Message body

thanks in advace for the help[/list][/code]