Despite its remoteness, Patagonia is surprisingly easy to travel. It's entirely feasible to plan a circuit that loops through, for example, Ushuaia, Punta Arenas, Torres del Paine, and then El Calafate and El Chaltén. There's so much to see and do here, you'll really want to include a visit to this region in your trip to Chile, if possible.
How much time you plan on spending in Patagonia is entirely up to you. If you're planning a backpacking trip in Torres del Paine, for example, you'll want to spend between 5 and 10 days there -- but those with plans for a few light walks and sightseeing drives in that national park might find that 2 to 3 days are enough. A quick trip to Patagonia might include 2 days in El Calafate, 3 in Torres del Paine, and a full day in Punta Arenas. A longer journey could begin with several days in El Chaltén, 2 in El Calafate, 5 in Torres del Paine, 2 in Punta Arenas, and a flight or cruise to Ushuaia for 3 to 4 days, returning overland or by plane.
Prices jump and crowds swell from early November to late March, and some businesses open during this time frame only. The busiest months are January and February, but these summer months are not necessarily the best months to visit Patagonia, as calmer weather prevails from mid-October to late November, and from mid-March to late April. And winter travel is growing in popularity.
Calling Between Chile & Argentina -- One would think that two neighboring countries would offer low telephone rates for calls made from one to the other, but not so with Chile and Argentina. Visitors can expect to pay the same or higher rates as a call to the U.S., often around $1 (50p) per minute. When calling from Argentina to Chile, first dial 00-56, then the area code and number. The prefix for Chilean cellphones is 09, but callers from Argentina have to drop the 0; so to call a Chilean cellphone from Argentina, dial 00-56-9, then the number.
When calling from Chile to Argentina, you must first call whichever carrier you're using (ask your host, your hotel, or at a calling center for the carrier prefix, usually either 123, 181, or 188), followed by 0-54, then the area code and number. Argentine area codes always begin with a 0 prefix, which you'll drop when dialing from Chile. For example, if dialing from Punta Arenas, Chile, to Ushuaia, Argentina, you'll dial 123 (or whichever carrier you're using), then 0-54-2901 and the number. When dialing Argentine cellphone numbers (which begin with 15), drop the 15 and replace it with the region's area code.