Does one need SIM car if only using phone without service

[John1397]

I use my smartphone with a sim for taking pictures and storing info from computer no voice or data plan can I take out the sim card and will the phone work like if you just wanted to use it as a calculator?

[Geek-9pm]

No, I use smartphones without the SIM installed. Of course, you can not use it as a phone. But your can use it as:
  A flashlight
  A clock
  A calendar
Now if  Wi-Fi is working you can:
  Surf most web sites.
  Check your e-mail
  Get the weather
But if you want a SIM, you can get one for $1 from:
https://www.freedompop.com/
I DO NOT endorse this company. I had to order twice to get one. 
But if it works, you have some free calling some of the time. Sort of.

EDIT: A few phones do not use SIM.

[Salmon Trout]

Yes, I use my old smart phone as an alarm clock, camera, mp3 player and wifi webcam. No SIM installed. It can plug into a computer by USB and transfer pictures and music back and forth.

[strollin]

An old phone can also be used for GPS navigation as long as you use an app that doesn't rely on cellular to download map data (such as Google maps).  An app such as CoPilot stores all of its map data locally on the phone and doesn't require a data connection to work.

[Isis]

Can also use it for an "Address Book".

[Salmon Trout]

Or voice recorder, or FM radio, or camera, or compass if it has a magnetometer sensor.

[Geek-9pm]

So yes, you can do things without a SIM card.
But why not just get a new SIM card?
Unless the phone was lost or stolen, you can put a new SIM card inside.
From an advertisement...

If you already have an unlocked GSM phone, this Ting GSM SIM card is all you need to get started with Ting. What's more, because the Ting GSM SIM Card is die cut to fit every common SIM card format from full-sized to the super miniature nano SIM, it will fit your device's SIM card slot without you needing to break out the ruler and scissors.   ... 

Prices vary. Check around.
AT&T:
https://www.att.com/shop/wireless/devices/simcards.html
T-Mobile:
http://www.t-mobile.com/offers/deals-hub.html?cmpid=ADV_PG_p14331172726_Q416HOLGIF&gclid=CPmZ3JOH4NACFQ8Hfwod9H0K2A&gclsrc=ds
Best Buy:
http://www.bestbuy.com/site/mobile-phone-accessories/sim-cards/pcmcat265100050014.c?id=pcmcat265100050014

You can get a SIM card for as slow as $1and have a old phone you can use as a backup.  I got a SIM card from Freedom Pop for $1 and sometimes it works.
https://www.freedompop.com
So, just get a SIM card.

[Isis]

"But why not just get a new SIM card?
Unless the phone..."

Because there are more new uses that can be fleshed out of phones these days, instead of only using it for "phone". I use mine for internet sometimes, but I still prefer a computer. Also, I like Salmon Trout's ideaof using it to play MP3s.

[DaveLembke]

Additional Smart Phone ability without a carrier and without a SIM card:

Adding here that I have an extra android dualcore arm processor phone not activated with phone service carrier crunching data for BOINC Asteroids project. Also got a tablet with android 4.0.4 for free from a person that upgraded to a tablet with android 6.x.x and no longer needed it which has a quadcore arm processor that also crunches numbers with 4 watts of power draw. I get about 1550 points a day from the arm processors that are crunching data. Not a lot of processing power, but they work. http://boincstats.com/en/stats/134/user/list/0/0/3073/0

When not using your phone or tablet when its charging you can have it run BOINC projects when the battery reaches 100% full, it then activates to crunch data, so while plugged in and charging it crunches calculations, and then you unplug it from a charger it pauses the number crunching.

[Geek-9pm]

Choosing BOINC projects
BOINC is used by many volunteer computing projects. Some are based at universities and research labs, others are run by companies and individuals. You can participate in any number of these projects.
Reference:
https://boinc.berkeley.edu/projects.php