Send free SMS messages to GSM cellular phones

A GSM SMS gateway is a Web site that lets you enter an SMS message to someone within the cell area served by that gateway or that acts as an international gsm sms gateway for users with roaming capability. Many Mobile Service Providers allow free GSM SMS Gateways around World.

SMS GATEWAY : WHAT IS SMS GATEWAY ?

SMS Gateway is a Technology which enables us to send and receive text & binary Short Messages over GSM / PCS digital cellular telephone networks. This solution consists of both an interactive messaging application with full source code, & a stand alone messaging gateway to other Windows applications through the use of OLE, DDE, and Command line interface.

SMS Gateways also supports POP3 for message transmission, and SMTP servers for message reception, so SMS gateways may be integrated with any e-mail environment without need for specialized custom development.

MMS GATEWAY : HOW DOES MMS WORK ?

MMS is implemented using a combination of WAP and SMS technologies. MMS enables multimedia messages containing content such as pictures, graphics, music, images, and ringtones. The MMS standard, based on 3GPP & WAP Forum standards, includes an MMS mail client on the device, a WAP - gateway for sending & receiving messages & a multimedia messaging service center ( MMSC ) for storing, transcoding and relaying messages. The process of delivering an MMS message to a mobile phone handset works like this:

1) It starts with a content file that contains the content of an
MMS message. This message may have been created by an application, or it may have been created by a user sending the message from a mobile phone. (when the message is sent from a mobile phone, a mobile phone connects to an MMSC via WAP and transmits the MMS message content to an MMSC & the MMSC then takes responsibility for further delivery.)

2.) The MMS message content is published (usually by an MMSC) so
that it is accessible via a URL.

3.) An MMS notification message is sent to the recipient mobile
phone, encapsulated in a WAP push message, which itself is encoded
as a binary SMS (the WAP protocols define an encoding for WAP push
over GSM SMS). This MMS notification message contains header
information about the MMS message, and a URL pointer that tells
the mobile phone how to retrieve the MMS message content.

4.) The recipient mobile phone opens a WAP session, and retrieves
the MMS message content from the URL contained in the MMS
notification message.

That's pretty simplified, but that's a good brief overview. In
most of the cases above, the WAP sessions are TCP / IP over GPRS
(although this is not an essential requirement).

List of free SMS gateways in Usa and Canada.