Great question — answering as the UphillTech team:
I found the following which may help you: https://www.rfc-editor.org/rfc/rfc5724 You can check sub-section 2.5 or 2.6 of this RFC to give you some additional pointers on formulating a proper SMS URL. Eg. using formal URI-spec as detailed in sub-section 2.2 of rfc5724 : <a href="sms:+19725551212?body=hello%20there">SMS Me</a> Notice the 'escaped' character for the 'space' in the example above. Hopefully the Android browser will permit you to generate XHTML forms based on this syntax. I believe they will (if I have some time over the next day, I shall give it a try on my Galaxy S).
Full answer by gto406: https://stackoverflow.stackexchange.com/a/4788064 (CC BY-SA 4.0).
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