That's an interesting question. It never occurred to me that I could install a SIP app on my iPhone and then receive calls to my Voipo number directly through that. I will have to try that.

I actually would expect that this works without problems (if you have the right SIP app that can be configured for Voipo). The softphone app on my Mac can be used for incoming and outgoing calls. Incoming calls ring simultaneously on the softphone and the cordless phone that is connected to the ATA. Why should this be different with an app on a different device in a different wifi net?

Are there people here who did this and can share their experiences?