Skype CANNOT be used for emergency calls, so you have two options:
- Rely on goodwill and no plan. Cellphones let you make emergency calls no matter what, plan or not.
- Go with the cheapest "normal" plan: Speakout 7-Eleven is $25 and the minutes last 1 year. This lets you have not only emergency calls but free incoming text and the ability to make calls if you are really stuck and have no Wifi access.
To use this Skype cellphone plan, NEVER answer your phone. Your missed calls log will show who's calling you. Then, when you get to a free Wifi source, call them on Skype.
If you are at home, you may consider investing in a cheap router so that you can use your own home internet service to broadcast your own private Wifi -- why pay for data on your phone when you're already paying for it for your home internet?