Send SMS Text Messages from Your Computer to Any Mobile Phone With Outlook 2007 and Microsoft SMSOfficer
With Microsoft Outlook 2007, you can easily send (or receive) SMS text messages from computer to any mobile phone - just write a new SMS text message (like the way you compose emails in Outlook) and hit Send.
Similarly, you can also forward emails, pending tasks and calendar items from Outlook to your mobile phone via SMS.
How to send SMS text messages from computer using Outlook 2007 ?
To SMS enable your copy of Microsoft Outlook 2007, first register your mobile phone number at SMSOfficer. This new service from Microsoft supports almost all cellular operators in US and other international countries including India.

You will soon get an SMS verification code on your mobile phone, confirm and the SMS feature is activated in your Outlook without you having to download any additional software - you will need to click on a configuration link which sets the entire configuration for you.
Forward Emails as SMS Text MessagesTo compose an SMS message in Outlook, select New -> Text Message. Outlook is automatically set up to use the standard text message limit of 160 characters. If your message exceeds the 160 character limit, the extra characters are truncated and delivered as a separate text message.
There are no registration charges and you also get 10 SMS credits for free at the time of joining SMS Officer. Once you exhaust the free limit, you need to pay for using the Outlook SMS service - payment can be made via PayPal.
When the other person replies to your SMS message, it will arrive in your mobile phone. Am not sure if you can use Outlook 2007 to send bulk SMS messages - i.e., one SMS message addressed to multiple recipeints.
Resources: Microsoft SMS Officer, Microsoft Training, Ellen Adams

does the service supports MTNL ?? MTNL provides SMS option from Landline in Delhi ( probably in other cities too ) .
There seem to be quite a few websites that offer free SMS sending options. What is the main advantage of smsofficer, other than using Outlook 2007, if we are to pay using paypal?
Yup very true whats the advantage when many sites like way2sms.com and rediff,many more are providing unlimited messages for free.As u said,By this we can send only 10 there after we will be charged so ca you tell more advantages of using this.
This service is NOT from Microsoft.
There are innumerable sites offering this service for free. There is no big advantage with this because from the 11th sms, you are charged.
You can do this for free using any email client. You simply figure out what the carrier of the person is you are sending to, and use the providers SMS email address. Granted, this only works if you know the person’s service provider, but it is completely free.
I recently posted a list of SMS email addresses for the various providers in Canada and US.