Google is your friend. Found these right on the Palringo FAQ page:
1. Will Palringo send SMS messages?
Palringo connects through the internet and doesn't use any SMS messages. If you pay for data usage, such as on a mobile phone, check with your network operator for pricing information. We recommend getting an 'Unlimited' data plan if you will be using Palringo a lot.
2. How does Palringo connect?
Palringo connects over the internet and will not work through a proxy. If you are using Palringo on a mobile phone then it will only use the phones data connection, whether that be WiFi, GPRS or 3G (not WAP) for example, and does not send/receive any SMS messages.
