Square might work. I hardly use a cell phone though.
PayPal so far is excellent, although I haven't had to handle a void transaction get. But their rules and are very clear and much cheaper than credit cards. As a plus, the way they handle charges, the only non-tax deductible charge is their 30 cent transaction fee. The credit percentage fee which is only 2.6% and deducts from taxes.
The bank was charging nearly $30 a month in non-deductable fees plus a 5% of transactions. I suppose large companies get a much better deal, but they obviously don't want small accounts these days.