STEVAL-FKI868V1 with NUCLEO-L152RE board.
Can be used “normally” or via mbed.
ST Page: http://www.st.com/en/evaluation-tools/steval-fki868v1.html
Sigfox page: https://partners.sigfox.com/products/steval-fki868v1
Schematics in the datasheet or here: http://www.st.com/resource/en/schematic_pack/steval-fki868v1_schematic.pdf
S2-LP ULP transceiver page: http://www.st.com/en/wireless-connectivity/s2-lp.html
STMicro Wireless Connectivity for IoT Applications Brochure: http://www.st.com/resource/en/brochure/brwireless_web.pdf
! many thanks to STMicroelectronics