Blackberry is special service connection internet which serve esspecially for cell phones.
Blackberry Successfully survive for by tens years serve push mail.
We must know what advantages and disadvantages from BLackberry before deciding use it.

Some advantages from Blackberry are :
1. Push Mail
Success key Blackberry there is It's great service, It has information
service from special server.That information is push mail.
Push Mail service is Email service which server put mail from server and
deliver to our application. This mail will show in cell phones real time like
when we receive SMS.
Push Mail system different with pull mail. Pull mail is system usually we use
like yahoo mail, HotMail, etc. We must access that website mail to know how many our inbox and read via browser or outlook application.
Receive mail method in Blackberry doing by Blackberry server but still use
GPRS channel.Although like that, when Blackberry services active, data traffic
using GPRS doesn't count conventionally from operator.
So' Blackberry services can't free.Each operator using various price for Blackberry,We can using that services appropiate with our ability.
There is two type Blackberry services, that is BES(Blackberry Enterprise Services) and BIS(Blackberry Internet Services).
For people who want to get push mail services for they email, they can using BIS, and for corporate can use BES.

2. Network Application
Many third party which develop application for network facility like Yahoo Messenger, and Facebook include in Blackberry services so we can free using Yahoo Messenger and Facebook.This services doesn't count how much data for download and upload for that services.