Hi shizadmen, it seems that the Apple Support has deleted my reply (Ph@Apple on Nov 30 see below) because they thought i was doing advertising ( yes i wrote down the address of a software that may solve your pb but I have no relation with the sw developer, I'm not even a customer...).
Anyway you can find such software by asking one of your prefered search engines with the keyworkds used in your question.
If you want to see the message I got from the Apple team:
"Dear Ph@Apple,
Apple removed your post titled, "Re: How to transfer SMS from iPhone to computer? Who can help me?," because it contained advertising.
Our terms of use, which include helpful information about using Apple Support Communities, is located here: https://discussions.apple.com/static/apple/tutorial/tou.html. We encourage you to continue using the Apple Support Communities while abiding by our terms of use.
We are including a copy of your post at the end of this email for your reference.
If you would like to send feedback to Apple about a product, please use the appropriate selection here: http://www.apple.com/feedback
As part of submitting feedback, please read the Unsolicited Idea Submission Policy linked to the feedback page.
Best Regards,
Apple Support Communities Staff
++++++++++
This message is sent from a send-only email account. Any replies sent to this address are deleted automatically by the system.
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A copy of your message for reference:
Hi shizadmen, try this one http://www.************ don't know if it works for 3gs but the demo version for iPhone 5 seems to answer your question. best, Ph