GSM-7 conversion- and septet-encoding library in Ruby?

Question

I am looking for a pure Ruby solution to convert UTF-8 to GSM-7 and back, and do septet encoding/decoding along the way.

Background here is: Sending and receiving SMS via a gateway and via REST-requests.

I found a solution with libiconv (http://mobiletidings.com/2009/07/06/gsm-7-encoding-gnu-libiconv/) (which works more or less, but is not accepted into libiconv itself due to certain deficiencies).

I would prefer a pure Ruby solution, most probably with a lookup-table for conversion and a 7-8 bit encoder to handle the resulting septets.

Anyone out there already did this? Any pointers?

Thanks, Tom!