just reliable, works with android and iphone, fast, inexpensive, and can be customized.  

When you DO look into what they do with the 2x of their income that they're not paying you for rent, you're going to find a bloated car payment or two, iPhones instead of Android phones, rental payments on furniture, carried monthly balances on credit cards, fanatic brand loyalty in food shopping...my point is that they fritter their money away and are typically left with nothing, month after month.Emergency fund?

I use a basic android smartphone from Walmart that costs me $45/month for data.

On a similar note @Joshua Dorkin what about an Android app?

I have an android and feel it will work as well as an Iphone will for business and personal use. 

I'm not sure if comments works on Android.

Why not just have your Android smart phone manage it.

If anyone is interested in downloading this mortgage calculator app for free, you can follow this link from your smartphone (only works on iOS and Android) --> Mortgage Calculator AppIf you like the calculator, make sure to post and let others know.

It connects to my android phone and will automatically log when I had a call or a text message with someone. 

You don't have to do the checking until you're thinking of renting to them so no money is spent here.Now, Google automatically uploads all your Android smartphone/tablet photos to the cloud these days.