Running VOIP phone from shared LAN on iMac 27" running latest OSX Mavericks

Hi, I´ve got a mid 2011 27" iMac which has been updated to the latest version of OSX Mavericks.

I connect to the internet over WIFI from the router and have shared the WIFI internet connection with the ethernet port to connect my Aastra 6730i VOIP phone.

I work from home and I am able to make outgoing calls no problem but cannot receive any incoming calls and the phone displays a "no service" message on the screen.

I do not know if this is a IP configuration issue with the ethernet port on the iMac or if it is to do with the config of the phone itself.

The ethernet is configuring the IP address on the iMac using DHCP and currently gives a self assigned IP of 169.254.xx.xx with a subnet of 255.255.0.0.

The IP address programmed to the phone is 192.168.2.6, subnet of 255.255.255.0, gateway of 192.168.2.1 and primary DNS of 192.168.2.1.

I used to have this working fine and able to make and receive calls without any manual configuration, the only things that changed recently are I updated to the most recent OSX Mavericks (10.9.4) (was running Mavericks 10.9.3 previously) and that we moved house, same iMac, same handset, same LAN cable, just unboxed it all and connectd it all back up same as before.

I am no networking pro and have tried everything I can think of so far, if anyone out there has more experience or knowledge and has any suggestions it would be greatly appreciated! (and no running a LAN cable from the router direct to the phone is not an option)

Thanks in advance