Get a free Google Voice account. That gives you an actual phone number
to which you can receive calls and also make them. VOIP apps work over
the Internet to connect to other VOIP endpoints. That won't work to
call someone's phone number or let them call you from a phone number.
Install the Google Voice app on the smartphone and configure it. If you
want every callee to see your Google Voice number (instead of the
Voice2Go number mentioned below) then configure the Google Voice app to
handle all outbound calls. The outbound call (whether via cellular
voice or wi-fi voice) goes to a Google POP (Point of Presence) at a
telco they choose and changes the Caller ID info to make it look like
the call originated from your Google Voice phone number. However, what
you see in your phone's display is you calling the Google Voice center
rather than the person you are calling.
Then install the Google Hangouts Dialer app. The Google Hangouts apps
is probably pre-installed but you need to add its Dialer companion app.
Now you can make phone calls via wi-fi from the phone to call the phone
numbers of anyone with one, and callers can call you from their phone
number.
Because Google Voice has voicemail, you get alerts when someone left you
a message. Either the Hangouts Dialer via Hangouts will tell you about
the new voicemail or you can configure Google Voice to send an e-mail
alert (i.e., you get an e-mail about new voicemail).
To get the full benefit of SMS in the Hangouts app, change your Google
Voice account to use Google's Hangout service. Then you can use either
the Google Hangouts site (
hangouts.google.com) or the Hangouts app to do
texting.
You should also check who is the ISP at his home. If Comcast, they have
their own wi-fi app to make calls (to and from phone numbers, not just
VOIP users). The problem is that a phone number has to be assigned to
his member account at Comcast. Since he is not paying for Comcast, get
his parent(s) to create a Comcast member account for him (if he does not
yet have one) which lets him have his own e-mail account there. Once he
has a member account, have the owner go under voice settings in their
account to create a new Voice2Go phone number. This is free. An owner
can create up to 6 Voice2Go numbers. You have to wait after issuing the
request for it to change from Pend status to Assigned status. Then the
owner can assign one, or more, of the available non-pending Voice2Go
numbers to the owner account or to any of the member accounts. If that
account is ever deleted, the Voice2Go number assigned to it is lost,
too.
After getting the Comcast/Xfinity account configured to add to it a
Voice2Go number, install Comcast's Connect app where you can do texting.
When making an outbound phone call, a prompt will appear asking which
dialer you want to use to actually make the call. Select the Connect
app to make a wi-fi call. Incoming calls to the Voice2Go number will
ring the app. Voice2Go includes voicemail, too.
If you are never going to add cellular voice service to the phone, when
the prompt appears asking which dialer to use then select the Connect
app and tap on the Always button. That will eliminate seeing the prompt
each time; however, you will have to clear the app's data (and have to
reenter your account login) if you ever want the prompt to reappear.
When I make a call, I get an intervening prompt asking if I want to use
Phone (built-in cellular phone service), Connect (Comcast's wi-fi), or
Google Voice (wi-fi calling). I do NOT click on Always because instead
I always want to see the prompt of which dialer and access method to
use. Even if I have cellular phone service and get a good signal
wherever I happen to be, I might want to save on my cellular call
minutes by using wi-fi if available. I don't bother with overpriced
unlimited calling plans. I use Tracfone whose unused minutes rollover
(as long as I keep an account open with them). I don't make that many
calls so I always have lots of unused minutes to rollover into the next
subscription. So the parents could get a Tracfone account for their kid
and not pay much but the kid could save those limited minutes for more
important calls and use wi-fi calling to make/receive calls - but that
only works if he is in range of a wi-fi hotspot. He has a hotspot at
home but when away from home there are lots of free wi-fi hotspots.
They are not as pervasive as cellular coverage and why having some
cellular call time would still help, like when the kid has an emergency
and needs to call home or anytime he is not in wi-fi range.
With wi-fi calling (not VOIPing), I use little of my cellular call
minutes, so I get a lot of rollover with Tracfone. In fact, at my home,
I have to use wi-fi calling. Signal strength at home for cellular voice
is way too weak. I don't get incoming calls and outbound calls are
unreliable (might not be able to start a call or it cuts up or
disconnects during the call). So wi-fi calling using Google Voice and
Hangouts Dialer is how I do cell phone calling via wi-fi from home. I'd
have to install a tall antenna and amplifer costing several hundred
dollars to maybe get a better cellular signal at home. Don't need to
waste the money and instead use free Google Voice service with the
Google Voice and Hangouts Dialer apps on the smartphone and, as a
backup, also have a Voice2Go number assigned to my Comcast account and
use their Connect app on the smartphone. I have 2 means of wi-fi
calling (in and out) which connects to phone numbers.
VOIP limits me to other users with VOIP apps. I did have the Skype app
installed along with a Microsoft (Outlook.com) account. The number of
folks that also had Skype that I wanted to talk with was a very small
community (less than the fingers on one hand) so it got little use.
Because it got used so little meant I was clumsy at using it. I did buy
3 years of Office 365 subscription which gives me something like 60
minutes of free calling (to phone numbers, not just VOIP) per month but
I never ended up using it. The other above mentioned wi-fi calling
setups were easier to use. Without the included phone minutes, all I'd
get with Skype is VOIP and that doesn't interest me nor do I know many
folks (that I want to talk with) that have Skype. I used to leave Skype
installed as yet another backup wi-fi phone calling setup; however, I
grew weary of it always crashing soon after powering up the smartphone
(I'd get a message that com.<something>.skype had stopped which meant it
was useless), so I uninstalled it. I really didn't need a 3rd wi-fi
calling option, especially one with limited minutes per month, when I
had 2 free and unlimited wi-fi calling options (Google Voice, Comcast).