Subscriber Identity Module (SIM)

A SIM card is short for Subscriber Identity Module card. It is a tiny encoded circuit board which is fitted into GSM cell phones at the time of signing on as a subscriber. It holds the details of the subscriber, security data, and memory to store personal numbers. A SIM card can stores any type of information Which helps the network service provider to recognize the caller.

A SIM card is a removable memory card and can be put into any compatible GSM handset, permitting the user to keep the same number while changing handsets. It is a standard unique chip which is a must in every GSM cell phone.

The working of a SIM card
A SIM card works as a digital brain of a cell phone. The validation and encoding ability of a SIM help to stop your cell phone from being stolen and your conversations from being overheard. The SIM card can store personal data, user ID and billing information and can be interchanged between phones. So you can easily receive personal calls even while using someone else phone just by installing your unique SIM in that cell phone.

Some cellular phone carriers cell phones in a locked condition. If you have such a cell phone, then in that case you can’t able to use different SIM cards without unlock your phone.

If you have a country specific SIM card, then you can use only in that country, you can’t use that SIM card in different country. A U.S. specific SIM card may give you limited coverage while traveling through Europe or some of the Greek Isles. Most country specific SIM cards have voice mail so a caller can leave you a message if your cell phone is turned off or not reachable.

SIMKey Keyring Databank
Ever misplaced your cell phone or had it stolen? Well, in that case buying a new cell is bad enough, you have to re-enter all you contacts in your new SIM card, its very difficult task to do. A SIMKey Keyring Databank is a novel device which helps you to backup your SIM data so that you never have to worry about losing vital information. You simply put your SIM card into this device, follow the simple directions and have a backup SIM card ready.

SIM cards are used with carriers that operate on the Global System for Mobile Communication (GSM) network. The competing network is Code Division Multiple Access (CDMA), a technology created by U.S. company Qualcomm. As of fall 2005, CDMA cell phones and CDMA carriers do not support SIM cards in most parts of the world, though this is changing. A CDMA SIM card called the R-UIM (Re-Useable Identification Module) was made available in China in 2002, and will eventually be available worldwide. Expectations for the future include a cell phone market that supports both SIM (GSM) and R-UIM (CDMA) cards by default.

Personal Digital Assistant (PDA)

A PDA (Personal Digital Assistant) is a computer that fits in your hand. These small computers are sometimes called palmtops and are a great way to store telephone numbers, email addresses, access the internet, make calculations, keep a digital calendar and play games.

PDA has a small screen usually bigger than a digital phone. While components and specifications change throughout the years, today you can find PDA’s with lots of RAM memory, storage in either miniature hard drives or compact flash cards or sticks and some can be expanded by a PC card that fits into a PCMCIA slot. Newer palmtop computers have USB ports to plug in a variety of peripherals to use with your PDA.

Below are some typical features you will find in modern PDAs

• Integrated WLAN adaptors

• Integrated microphone and speaker

• 240×320 screen resolution

• USB ports

• Microsoft Outlook

• Microsoft Internet Explorer

The operating systems are specially designed for PDAs, the performance depends on the processor speed and memory, a typical PDA would boast a 300MHz processor and 64MB of ram.

The main purpose of a personal digital assistant (PDA) is to act as an electronic organizer or day planner that is portable, easy to use and capable of sharing information with your PC. It’s supposed to be an extension of the PC, not a replacement.

All PDAs come with some kind of personal information management (PIM) software that typically handles the following tasks to keep you organized:

• Store contact information (names, addresses, phone numbers, e-mail addresses)

• Make to-do lists

• Take notes

• Track appointments (date book, calendar)

• Remind you of appointments (clock, alarm functions)

• Perform calculations

Run Application Software
PDAs can run specialized software applications:

• Windows Mobile devices come with Pocket versions of Word, Excel, Internet Explorer and Outlook (includes e-mail and PIM functions), along with Windows Media Player and voice memo recording.

• Most Palm OS devices include applications such as DataViz Documents to Go (compatible with Microsoft Word, Excel, and PowerPoint), palmOne Media (for photos and video), VersaMail e-mail software and web-browsing software.

• All types of devices can run other kinds of software including games, multimedia, expense, diet and exercise, travel, medical, time and billing, and reference.

Synchronize With PCs
Because PDAs are designed to complement your PC, they need to work with the same information in both places. If you make an appointment on your desktop computer, you need to transfer it to your PDA; if you jot down a phone number on your PDA, you should upload it later to your PC.

Synchronization software on the PDA works with companion software that you install on your PC. Microsoft Pocket PC devices use ActiveSync and Palm OS devices use HotSync synchronization software. On your computer, you also need an application like Microsoft Outlook or the Palm Desktop that holds PIM information on the PC side.

The beauty of synchronization is that you always have a backup copy of your data, which can be a lifesaver if your PDA is broken, stolen, or completely out of power.