The SMS-GW3 is 100% backwards compatible with the current SMS-GW2.
http://www.hw-group.com/products/HWg-SMS-GW/HWg-SMS-gateway_en.html
New SMS Gateway is available now
The HWg-SMS-GW3 device is central GSM gateway for text messages (SMS) from other HW group products. Third generation is smaller, more cost effective and is available now.