I don't have an Iphone but my sister does and you can set it up for Skype - I don't know if that is helpful to use in the situation you describe or not. But to rent 5 cell phones will probably be a lot more than an occasional call if someone is lost....Some hotels have wi-fi but there is also a router that you can buy to make your room into a wifi area - a friend of mine uses it in Japan with his Iphone

The N'Ex takes about an hour to get to Tokyo station - there are other train options as well - depends on where your hotel is...

The problem you may have with your phones is that free WIFI that doesn't require registration in Japanese and that is not location limited is scarce. If you use roaming to allow you to access the phone network, you could incur a huge charges for data just through location services. We pay a set fee for data charges of ¥4,400/month but see itemized on the bill usage of often over ¥1,000,000 in data each month. We do use our iPhones a lot, but even if you used yours 10% of what we do, it would be ¥100,000. That is per phone!

Perhaps ATT has global roaming packages? Or you could consider renting phones or routing devices here? It may be the same cost to rent a phone or a router. B mobile, Softbank, Rentafone are 3 companies...but there are many more.

With 5 people, it may be just plain easier and not much more money to use a transfer service like Tokyo MK or Tokyo Airporter from the airport.

Yes, KimJapan, thanks for explaining that....I found this message on another discussion board but again wifi is necessary:

"I just came back Japan with my US iPhone 4. As long as you turn off your data and text/voice roaming, and only have wifi, you should be able to text for free. Just make sure that the other person has a non-jailbreaked iPhone and that the message bubbles are blue. Here's a link to a thread on the apple website: https://discussions.apple.com/thread/3754573?start=0&tstart=0"

I travel with my company iphone and the company buys me a data plan from ATT. The Intl phone plans are cheap at 5.99 per month which entitles you to calls at a discounted rate and you can add the additional service to your account and discontinue service when you return. The data plans however are not cheap. It depends on how long I am there for but I find that when I am there for a month I need the 275 mb plan at 99.00/mo which again you can start when you leave and remember to cancel when you get home. There are ways to control how much data you receive. Last Nov we stayed for three weeks and I got the 125 mb plan at 49.00 per month. I just travel around with my iphone on airplane mode until I am in a free wifi environment or I need to use the phone.

Here are a few tips while using your iphone internationally from ATT:

If you do not want to receive email automatically
If you do not want to receive email automatically, disable your device’s auto-check functionality.
You may then utilize Wi-Fi as a supplement to 3G/GPRS/EDGE to download and manually check email.
Wi-Fi is available in many international airports, hotels and restaurants.
Tip for iPhone Users
To turn off the auto-check functionality, tap on: Settings>Mail, Contacts, Calendars>Fetch New Data.
Toggle “Push” to “OFF” and under “Fetch”, select “Manually”.
Tip for Android Users
Select: Settings > Accounts and sync > Manage Accounts. Un-check “Auto-sync” to cancel all auto-sync functions (email, weather, stock quotes, etc.) or select specific account and uncheck sync options.
Tip for Windows Phone 7 Users
Select Settings > email & accounts, then select an account. Choose “Download new content” and set to “manually”. Uncheck all “Content to sync”, then click checkbox at bottom of screen to save changes.
Other Devices
Consult your user guide. If you want to place calls but not use data:
By default, the setting for international data roaming will typically be in the "OFF" position. Check the
settings on your particular device before traveling abroad. Turning data roaming “OFF” blocks email,browsing, visual voicemail and downloads, but it will not block text messages. International roaming rates apply when you send text or picture/video messages.
Tip for iPhone Users
Tap on: Settings>General>Network>Data Roaming (toggle to “OFF”).
Tip for Android Users
Tap on: Settings>Wireless and network>Mobile networks>Data roaming (uncheck it).
Tip for Windows Phone 7 Users
Tap on: Settings>cellular>Data roaming options (select “don’t roam”).
Tip for Blackberry Users
Tap on: Settings>Mobile Network>While Roaming (select “Off”).

The Int'l phone plans are cheap and give you a peace of mind(emergencies) while on your trip. Just remember not to use your phone as you would at home. I also rented a phone and a Type A) B-Mobile pocket WiFi from Rentafone Japan and was pleased with both the service and the ability to connect to wifi anywhere with our iphones.

http://www.rentafonejapan.com/Mobile-Internet.html

Aloha!