Where I am, simply making calls over IP is not enough to qualify a device as a phone.
If it cannot phone the local police station, the local pharmacy or the local clinic, it's not really a phone.
It can if you have a SIP provider. The only limitation depending on your provider might be emergency numbers.
What it is not is a mobile phone. But it is totally a SIP phone.
If we're getting technical it is a mobile phone, just not a cellular phone. A cellular phone will work anywhere it can get a compatible cellular signal and this will work anywhere with decent WiFi.