PPCGeeks - SVP Server settings?

Is anyone out there using thier PPC to talk VOIP on a wireless network with a softphone application? To my knowledge most softphones out there dont have SVP server settings available in order to be used. I think some of the ones that do are propritary to specific IP systems and are not free or for general use. Anybody got any bright ideas or applications to use? Specifically, we use Avaya IP Office and Spectralink SVP Servers. I would like to use my PPC on this instead of buying an expensive softphone or using a more expensive handset. Thanks for any suggestions or experiences...