I have a Samsung Galaxy that was gifted to me by my son after he upgraded.
The only reason I have it is to play with it. ..... not games ..... but just trying out stuff on it to see what works well and what doesn't.
I rarely make calls using it ..... but when I do I tend to use Linphone and make the calls over VOIP.
That allows me to call any one else who has a VOIP number without cost.
Of course I need to be within wireless range of an internet connection for this.
Rarely it occurs that I am not within range, and then the 'normal' mobile phone network is used.
It is convenient to have several devices in one package, when out and about ...... GPS and Google maps and street view integrated, for getting to the correct address in a timely fashion ....... email ..... IM ..... SMS ........ VOIP ....... mobile network phone ...... flash light for emergencies .... and so on.
Oh yes ..... the text on the bigger screen makes it easier to see who is calling
When you say VOIP without cost...do you really mean without cost? I'm truly curious. As I said, after my daughters got their own smartphones (an iPhone and an Android something or other) my Verizon basic service plan comes in at $50-55 a month US (depending upon text messaging). The Verizon data plans seem a bit pricey. In my social circle I have maybe 12-14 people that I call/text on a regular basis; and to be honest the LG VX8300 is not great for texting.
My daughters and their significant others seem to be amused by my phone, but I don't have the pressing need to access my email while I'm away from home for a day (or two).
I guess that I'm so old school (perhaps just too old) to appreciate the apps of them thar newfangled smarty phones.
Calls between two VOIP clients are free from cost ..... except of course whatever internet connection is used .... in a similar manner to the way that Skype users can call each other without cost.
The difference when using SIP is that there are many providers of the service, and for the most part calls can be made between someone on one service to someone on another.
The service provider will also provide a means to call other phones such as landlines and mobiles, at a cost.
There are lots of options out there and a great many 'plans' from different providers, so you can choose the plan that suits your calling pattern.
For instance I use one plan that I pay a €10 payment to when I need to, and in return I can make calls to landlines in many countries worldwide, without cost for 90 days.
Calls to other phones such as mobiles will be charged and deducted from the payment.
If I do not use the €10 in the 90 days I have the option of not making another payment, and then all mobile AND landline calls will be charged and deducted from the balance, until used up.
Alternatively I can make a payment after 90 days, and get another 90 days of free landline calls.
Mobile call rates are typically 50% of what the normal providers charge for mobile calls, and about 2c per minute for landline calls, when out of free days.
I have the VOIP set up at home, and there I use a desktop phone as (apparently) normal, except all calls go out over VOIP.
I have the same settings in the Samsung and can use that at home or when travelling and within wireless access range.
I think that explains my setup .... but there are many ways to do it, depending on requirements.
Ask if you need clarification