From Chile Wiki

Voice Over IP (VOIP) now offers great savings over regular international phone calls with good quality and reliability. Such services have been tested to work well through Chilean broadband providers.

In October 2006, TDLC the Antitrust Court issued a pro-VOIP decision in Voissnet vs. Telefonica (CTC - Chile) that prevents ISPs from blocking IP telephony.

Vonage

Vonage uses ATA devices that let you connect your regular analog phone (wired or cordless) to a router. For a $25 flat fee per month you get unlimited phone calls to the US, Canada, and several countries in Western Europe. If you really call a lot this is probably the cheapest option out there.

The main challenge with Vonage is its long term viability as the company has been losing a lot of money since it launched.

Skype

Skype is the most popular PC-based VOIP program. Calls are free between Skype users, and inexpensive with Skype Out. Skype Out costs about 2 cents per minute to the US; there's no flat fee option.

With Skype In you can have a phone number in the US, the UK and a number of other countries. This will give an affordable way to call you in Chile for people back home.

With Skype To Go you get a local (i.e. Chilean) number, you call that number on your cell phone, and you get to pay SkypeOut rates for international calls. In other words you pay about 2 cents a minute to call a US or European landline from your cell phone in Chile. This costs $3 a month as part of the Skype Pro service.

Vonage vs. Skype

If you have a good analog cordless phone system and call the US more than a few hours per month, Vonage is a better and cheaper option. On the other hand, the Vonage softphone costs extra money so when all you have is a laptop (or PDA) and a wifi signal (typically if you're traveling in hotels or just getting settled), Skype is the better option.

Even if you're using Vonage, it's good to have a backup plan and sometimes Skype works better than Vonage for calls to Europe. Because Skype doesn't cost anything upfront, but because it also was completely offline for 24 hours in August 2007, it is recommended to be familiar with at least two VOIP services if they're your lifeline to the US/Europe.

Other options

There are plenty of other VOIP providers out there, Vonage and Skype are just the two better known. Software solutions similar to Skype include Yahoo Voice and FWD. Look for information about SIP softphones or SIP hardware for instance to find additional options, or read sites such as VOIP User, Voxilla, VOIP Info and SmallNetBuilder.

If you're a) not afraid of relatively technical matters (i.e. you understand a bit telephony and IP networks), b) you don't want to be locked in proprietary solutions, and c) you want to optimize your VOIP budget, then read this primer on how you can juggle several VOIP providers with voxalot.

Of course, in some cases you end up using the legacy landline and mobile networks. See Chile Phones, Cell Phones, and Communication