Update on Brazil info
 

I have checked the site and the info on the plans is outdated.

Well, let's go for the current info:

TIM
Name of prepaid offer: Infinity Pre

Tariffs: (all prices include Rio de Janeiro taxes)

Local calls to fixed landlines: R$0.50 per call (no timing)
Calls to TIM (on net) mobiles to any state in Brazil: R$0.25 per call (no timing)
Calls to other carriers (off net) local mobiles: R$1.59 per minute.
Long distance calls to other carrier mobiles: R$2.30 per minute.
Long distance calls to fixed phones: R$2.30 per minute.

Tariffs with taxes included for all states: http://www.tim.com.br/Portal_Conteud...finity-pre.pdf

Roaming:
Additional per call received: R$0.50 (per call)
Received call: R$1.99 (per call)
No roaming fees to make calls within Brazil using TIM network.

Data:
R$0.50 a day (10 MBytes at 3g speeds, then capped to 50 kpbs)
R$1.99 a day (80 mbytes at 3g speeds then capped to 50 kbps) . To activate send an SMS with ATIVARMODEM to 1616

SMS:
R$0.50 a day for any number of SMS, any carrier (on net and off net).

Recharge are available on most stores which accept credit cards for payment, they can usually issue electronic vouchers with the same machine, or you can buy cards at newsstands (they are not so common anymore, the physical ones), in R$13.00; R$18.00; R$27.00; R$35.00; R$50.00 and R$100.00.

The SIM card costs R$10.00 and comes with R$10.00 included. I don't know about microSIM avaliability, I had to buy one for myself in exchange for another postpaid line and they charged R$20.00 for the microSIM card only, they call it a "blank SIM" where they can transfer any account to it (either prepaid or postpaid). I guess if you need a microSIM you have to buy a regular one, and then pay another R$20.00 and have the number transferred to a microSIM chip, not sure though.

Claro offer
 

The offer by Claro is as follows:

CLARO
Name of prepaid offer: Claro Pré-pago Ilimitado

Tariffs: (all prices include Rio de Janeiro taxes)

Local calls to fixed landlines: R$0.50 per call (no timing)
Calls to Claro (on net) mobiles to any state in Brazil: R$0.21 per call (no timing)
Calls to other carriers (off net) local mobiles: R$1.60 per minute.


Roaming:
Receive calls: R$2.25 per minute of received call

Data:
R$0.50 a day (10 MBytes at 500 kbps) (default)
You can also use packs which you need to subscribe to.
150 Mbytes: valid for 15 days, price R$6.90, max speed 500 kbps.
300 Mbytes: valid for 30 days, price R$11.90, max speed 500 kbps.
100 Mbytes: valid for 30 days, price R$22.00, max speed 1.5 Mbps.


SMS:
R$0.50 a day for any number of SMS, any carrier (on net and off net).

Recharge are available on most stores which accept credit cards for payment, they can usually issue electronic vouchers with the same machine, or you can buy cards at newsstands (they are not so common anymore, the physical ones), in R$13.00; R$18.00; R$22.00; R$30.00; R$50.00; R$100,00; R$150,00.

R$18.00 recharges are valid for 60 days.
R$22.00 recharges are valid for 75 days.
R$30.00 recharges are valid for 90 days.
R$50.00 recharges are valid for 120 days.
R$100.00 recharges are valid for 180 days.
R$150.00 recharges are valid for 300 days.

The SIM card costs R$10.00 and comes with R$10.00 included.

You can check the balance dialing *555# you'll get an SMS with the balance.

OI
Name of prepaid offer: Oi cartão qualquer hora

Tariffs: (all prices include Rio de Janeiro taxes)

Local calls to fixed landlines: R$1.59 per minute
Calls to Oi (on net) mobiles to any state in Brazil: R$1.59 per minute
Calls to other carriers (off net) local mobiles: R$1.59 per minute

Roaming:
Receive calls: The company states no roaming charges within Brazil using Oi network. My personal experience it has been charged.

Data:
5 mbytes a day, for R$0.50 (send SMS with Oi to 3505).
10 mbytes a day, for R$1.00 (default offer)
15 mbytes a week for R$2.90 (send SMS with Oi to 3515)
30 mbytes a month for R$9.90 (send SMS with Oi to 3530).

All packages max speed 1 Mbps and capped to 50 kbps.
You can buy the package again as soon as it is depleted, no need to wait for the validity period to finish.

SMS:
R$0.42 per SMS sent.
They also have SMS packages which can be bought for use in a 30 period:
Pacotes de Torpedos SMS Oi Cartão ou Oi Controle

Recharge are available on most stores which accept credit cards for payment, they can usually issue electronic vouchers with the same machine, or you can buy cards at newsstands (they are not so common anymore, the physical ones).

The SIM card costs R$10.00 and comes with R$10.00 included.

You can check the balance dialing *804.
You can check the "bonus credit" dialing *805.

The mechanics in Oi are pretty hard to understand. Every month you recharge you get double the value of the recharge in "daily bonus", they give the same amount you recharged in "bonus credits" for every day of the month, so if you recharge R$20.00 you get R$40.00 daily to use in "bonus permitted expenses", the bonus can be used to call other local Oi mobiles, local Oi landlines, Long distance Oi landlines, long distance Oi mobiles, and SMS to any operator. Also these recharges must be between R$12.00 and R$25.00. You need to recharge by the 5th day of the month to get the bonus up to the 30 following days.

I really wouldn't recommend to a visitor, hard to understand and estimate expenses.

Vivo
 

VIVO
Name of prepaid offer: Novo VIVO Sempre

Tariffs: (all prices include Rio de Janeiro taxes)

R$7.90 once charged to subscribe to the offer Novo Vivo Sempre.
You need to charge at least R$13.00 a month to keep the offer active.

Local calls to fixed landlines: R$0.35 per minute.
Calls to Vivo (on net) mobiles to any state in Brazil: R$0.05 per minute
Calls to other carriers (off net) local mobiles: R$1.65 per minute.


Roaming:
Receive calls: R$1.65 per minute of received call

Data:
R$9.90 a month for 200 MB at 256 kbps then capped to 32 kpbs (default)

SMS:
R$0.05 per SMS to any carrier (on net and off net).

Recharge are available on most stores which accept credit cards for payment, they can usually issue electronic vouchers with the same machine, or you can buy cards at newsstands (they are not so common anymore, the physical ones).

R$3.00 or 5.00 recharges are valid for 1 day.
R$8.00 recharges are valid for 3 days.
R$12.00 or R$13.00 recharges are valid for 15 days.
R$18.00 recharges are valid for 25 days.
R$25.00 or more recharges are valid for 30 days.

The SIM card costs R$10.00.

You can check the balance sending a SMS with SALDO to 8011 you'll get an SMS with the balance.

Muito obrigado! :)

I updated the pages here: Brazil

Please take a look if there's still something wrong or missing.
Thanks!