Has anyone experience of using any of the sip softphones (such as sipdroid) for the android operating system. I'm thinking in terms of a data only contract on one of the new android tablet devices. I know the data service provider might want to block sip traffic, but would it be OK on wi-fi from a hotspot where one had access? I've read quite a bit about the Skype client for android, but my interest is for incoming calls to an established number that was recently ported to voipfone.