I have a little jigsaw puzzle I need help putting together.

The pieces are:
1) The internet
2) Telecom XT 3G account accessed via a USB 3G modem
3) A laptop running Windows XP with motherboard ethernet LAN connection.  Internet Cnnection sharing is turned on.  Static IP address on the Local LAN connection 192.168.xxx.10 subnet 255.255.255.0
4) Linksys AG310 (there is no W because its not the wireless one).  Connection is set currently set to RFC 1483 Bridged.  Have also tried Bridged Mode Only.  IP Address 192.168.xxx.11 Subnet 255.255.255.0
5) Linksys SPA2102 IP address 192.168.xxx.1 subnet 255.255.255.0
6) An Xnet VFX account with the MAC address of the SPA2102 configured.
7) An analog phone
8) Some CAT 5 cables
9) A house just next to the middle of nowhere sufficiently far from an exchange that ADSL is not an option but does have Telecom XT 3G coverage

On all pieces with IP addresses xxx is the same.

The picture in my head sees the analog phone connected to an adapter sending digital packets to the internet via the usb modem and the VFX account.  I am fully willing to accept that some of the above pieces may not be needed

The SPA2102 was obtained following advice from Xnet Support that the AG310 voip cannot access the internet via any connection other than its inbuilt ADSL modem.

Connections tried:

1) PC ethernet to AG310 ethernet, AG310 ethernet to SPA2102 Ethernet, SPA2102 Phone 1 to analog phone.  Under this connection the PC can see the web-based configuration pages of both the AG310 and the SPA2102.

2) PC ethernet to AG310 ethernet, AG310 ethernet to SPA2102 internet, SPA2102 Phone 1 to analog phone.  Under this connection the PC can see the web-based configuration pages of the AG310 but not the SPA2102.  

3) PC ethernet to SPA2102 ethernet, SPA2102 Phone 1 to analog phone.  Under this connection the PC can see the web-based configuration page of the SPA2102.

4) PC ethernet to SPA2102 internet, SPA2102 Phone 1 to analog phone.  Under this connection the PC cannot see the web-based configuration page of the SPA2102.

Under all connections tried, Xnet advises seeing no connections incoming from the SPA2102 MAC address or the XT assigned IP address.  This is confirmed by the SPA2102 voice configuration still being accessable in the web-based configuration page and no dial tone on the analog phone.

Xnet Support are unwilling to advise on the local area network configuration

Is the picture in my head acheivable with the pieces I have?  Am I missing any pieces?  Do I need to configure some of the pieces differently than their current configuration?