Sip From: address

I have an Asterisk PBX set up in a failover configuration so that the active server gets a floating IP address assigned. As an example, server-A may have an address such as and server-B has an address of The floating address for the active server assigned to the same interface is I also have a vlan and the same type of floating address is used for that. Because of the multiple addresses, I have bindaddr = in the sip.config. All of these addresses are assigned to the same physical interface. for Server one, eth0 = eth0:0 =
eth0.129 = eth0.120:0 = This is if server one is the active server.

The problem is that the server accepts traffic on, the floating address, but sets the From: address in a sip response to the address, in the case of server-A active. If I did not have a vlan network on I could use a binaddr = and all would be happy. If I could specify multiple bind addresses, this would also solve the problem, but I do not think Asterisk allows that.

So any ideas on how to force Asterisk to place the floating address, assigned to interface eth0 as eth0:0 in the sip message? Any ideas would be greatly appreciated.