Why do you need a cell phone away from home?

I'm wondering what the advantages are to a pre-paid SIM card and what they actually do. And why you would actually need them?
I would love to NOT check email while on vacation but if I NEED to, can I use a pre-paid SIM with a data package to do that?
I'm headed to Bali and then an outer island where I am assuming will not have cell coverage!

For many if not most people, you don't need them. However, as a matter of convenience, the local pre-paid SIM gives you access to call outbound to your home country without having to play games with finding a phone and access numbers on calling cards, and without paying exorbitant roaming fees from your home carrier. And depending on carrier, many do have reasonable data packages that will allow you to check and reply to email. Plus it can be nice to have data access for navigation apps on your phone, or to look up tourist information while you're there. I don't know much about Indonesian carriers, so I won't be much help on the specific coverage for your situation.

Perhaps this (very short) thread would be helpful: Pre-Paid SIM in Bali/Indonesia

if your phone has wifi you may not need a SIM. Just use the wifi to check your mail or whatever.

If my phone has wifi why would I need a SIM unless I was actually calling home?

Just to have connectivity when you're away from wifi hot spots.

According to my cell phone carrier, all data and voice is pay as you go if I use my current phone. I'm more into asking locals for directions than using a navigation app on my phone!
Tourist information? I'm sure that where I am staying does not have a concierge but I bet someone will let me know good places to go!

Are there good apps for finding wifi hot spots?

Pre-Paid Sims (local in the country you're visiting) are great if you need to call for a Taxi/Radio Car, Make reservations, contact another member of your party when separated. More convenient than having to find a (Free) wifi location to use skype if one's not readily available.

Not to forget inbound calls...people back home calling you.

If you are going to the Gili Islands, Gili Trawangan has a cell tower that covers all 3 of the Gilis. The Indonesians love their cell phones.

Depending on where you go and with whom, phone:
- can coordinate with travel companions, without having to either spend 24/7 together (OK with my wife but nice to have the option to get away, gets old almost immediately with any of the buddies I occasionally travel with) /or/ spend time sitting and waiting at prearranged rendezvous.
- in urban settings, often quicker to call a cab than wait in a taxi rank or wait for one to pass to hail one (if safe at all; some places I've been it's generally considered unsafe)
- restaurant reservations
- check in with family/loved ones at home or be reachable by them in emergencies
- if you're single and unattached, I'm told it's sometimes useful if trying to pick up local company

Data:
- Maps!!! Seriously, this one is rarely that helpful on wifi, as it's when you're lost -- rather than at a cafe -- that it's most useful ... and I haven't yet found a really good offline mapping app for outside the US.
- Search for local amenities/restaurants/transit... yes, you can ask for recommendations, but if the choice is some guy recommending his brother-in-law's place vs. the crowdsourced wisdom of the internet, well, I know which one I'd bet.
- Translation -- yes, there are phrasebook apps, but the ability to pull up specific requests/instructions on Google translate is SWEET. Plus, in many cases, if you can get a local keyboard (or you're going someplace they use our alphabet), a lot of people can answer by typing into the phone.
- Check in at home more cheaply without using minutes (wifi works for this one, assuming your hotel has it and has a decent connection)

Depending on where you go, the answer is usually yet. Certainly on Bali proper.

I've not been, but basic GSM cell coverage is available in surprisingly rural places these days. I wouldn't bet on any kind of high speed data, of course.

Let's see:

1. Send/receive email (personal only, no work when I am on holiday)

2. Look up information (exchange rates, train schedules, restaurants, banking, etc.)

3. Google maps.

4. Google translate.

5. Music and games.

6. Facebook.

7. Google Goggles.

8. Make/receive phone calls.

9. Other stuff I forgot.

With a "local SIM", the charges are a mere fraction of what they would be with roaming rates.

Ok. If I decided to get a local SIM, what would this entail? I'm really technology challenged! Do you buy a new phone like a pre-paid phone in the US? And how do you tell if it is a good carrier?
I guess I just don't understand the logistics! And what is a typical price?

First you need an unlocked GSM phone. If you have t-mobile or At&T you can ask for the unlock code. When you arrive you will see cell phone shops on most every corner. Go in and buy a sim card put it in your unlocked phone and you are off and running. The salesperson will set it up for you. When you start to run out of time go to any tabac shop and buy a top-up.

"Why do you need a cellphone away from home?" is the heading of this thread. I think the better question is "Why do you need a cellphone at home?" After all, the very purpose of a cellphone is to communicate when you are neither at home nor at your desk. I know life, and telephone technology, has moved on and that we are all dropping our landlines, but that remains the crux of the matter.

Just as many people have become habituated to having Internet access all the time at home (remember the dialup days when connections were metered?), people are used to having their smart phones and iPads with them all the time.

Yeah you can say you want to get away from it all for vacations but how much of our use of computers and mobile devices is for leisure, as opposed to for work?

I check my work emails on my iPhone while on vacation, using data that I've paid for. But I rarely if ever reply to any of them. But I get the data because I use it for a lot of other things.

For instance, I used it with Google Maps to navigate northern Italy. Didn't have to pack a Garmin. And often, the mobile network provided faster speeds than the hotel Wifi in many cases.