Siemens Gigaset SE505 v3

Model S30853-S1006-R107-4, T7/T8

On the OpenWrt wiki

Label shot, Internal shot More images (low res)

On the DD-WRT forums

"3028-001490 28-000270" is silkscreened on the board. The device is similar to the Belkin F5D7230-4 v2.