Siemens Gigaset SX763

More info and pictures here.

Only firmware version 4.x.x.x.x devices are described here (that is, v2 devices).
 * Per the OpenWrt wiki, v2 devices have part numbers following the S30852-S70x-xxxx pattern

S30852-S709-R331-5 and S30852-S706-R331-5 may be valid Siemens part numbers for this device.

On the DD-WRT forums

same model is manufactured in germany by both siemens and sagem, and in tunisia only by sagem

known MAC OUIs: 00:21:04, 00:26:91, 98:8B:5D, C0:D0:44