Just answered on another thread about telephones. I've had 4 or 5 phones of different models and quality from the US over the last 6 years here in Buenos Aires with no problems ever. Unless you have a really old phone that only works off of some US/Canadian providers' network specifically, you should have no problem with your phone. I believe most phones in the US nowadays are compatible as well with other network types like GSM, although I know it didn't use to be the case, but that was more like 10+ years ago.
As far as getting a rentista visa with business income alone, you won't be able to do it, as wreReynolds mentioned. And I have heard as you stated that the new requirement is on the order of 8000 pesos a month.
However, I know someone who is going throught he process of getting a rentista visa in a somewhat gray manner. He set up a corporation in Panama, set himself up as president, and shows via an accountant in Panama that dividends from the company pay him enough to qualify. He deposited enough money in the bank attached to his corporation to have the corporation send him transfers as dividends to an account here to prove his income.
It's not an easy process, and he's still seeking approval, but nothing has been rejected so far. I'm not suggesting you do this, but it may actually be the only chance you'd have to get residency, unless you marry a resident or citizen, or find employment with someone who is willing to sponsor you.
If you're not planning to stay here for a good while, I'd just stay in the country without a visa (as a local immigrations attorney in another thread advises, you wouldn't be illegal, just irregular - but realize that leaving and re-entering the country with such status could produce some small risk [as of now] that you may be denied re-entry, but it's a low risk at the moment) and deal with the expensive pay-as-you-go telephone and expensive grocery store purchases without a debit card from a local account to give you discounts, and have a hit-or-miss success with things like buying movie tickets over the internet with your international debit/credit card.
Also, be aware that for the long term, you will not be able to rent property with long term contracts without a property deed to guarantee your lease. You will be stuck with short term leases which are illegal for more than a 6 month term, although you may be able to find an owner who is willing to give you back-to-back 6 month leases. Rental laws here favor the renter much more than the owner and owners are terrified of someone moving into their property and staying there without paying, as it could take two or more years via the courts to get them out. Temporary leases at the moment are safer for the owners because they don't ahve quite the same effect as long term leases.
Make sure you know what you're getting into, moving here, for anything more than a relatively short term like a year or less.
