Does TI have a 900 MHz H/W and S/W ZigBee solution?
http://newscenter.ti.com/index.php?s=32851&item=123115
I don't know about TI's solution for ZigBee on SubGHz but you may want to check the following companies:
http://www.an-solutions.de/
and the following company that has a ZigBee sniffer for SubGHz networks:
http://www.perytons.com