Google will reportedly add SMS sending capabilities to Gmail Chat today which will now let desktop Gmail users swap instant messages with mobile phone users via SMS protocol. Previously Gmail users could communicate to mobile phone users, but were limited to sending e-mail messages. The Official Gmail Blog hasn't announced the new SMS chat feature yet but reports indicate that SMS support in Gmail Chat will be available for all US users some time today.

When the service becomes available it will require you sign up for it through Google Labs. To do this simply go to Gmail, then Settings (upper right-hand corner of Web page) and select Labs. Simply scroll down and "enable" SMS chat.

The new feature joins a plethora of new experimental features launched this month by Google Labs. SMS in Chat, according to reports, is only available in the US.

How SMS in Chat works

To get started using the service just type a phone number in the Chat search box or search a contact by name (if you have their phone number stored) and click the "Send SMS" option.

The person receiving an SMS from Gmail's Chat will see it as coming from a 406 area code number. This pseudo-phone number will be associated with your account once you first use the feature. That 406 number now can be used for others to send you text messages that will pop up right in your Gmail Chat window.

Potentially Harmful to Your Wallet

This feature is not free. The person receiving SMS messages from you via Gmail Chat will be charged by their mobile carrier each time you hit enter in the chat window. The same applies if they reply to that message. While sending the messages from Gmail is free, at the receiving end users will pay standard text messaging rates to their wireless carrier.

SMS in Chat is a feature that differentiates Gmail from other large webmail providers such as Windows Live Mail or Yahoo! Mail, which do not have such functionality. AOL's instant messaging platform AIM does support SMS messaging in chat.