MOD_GPS (uBlox 7020) - battery backup, Tx,RX voltage level

[TeleVox]

Hi,

1. MOD_GPS has in specification:
Internal Back-up battery 3.0V, 5.5mAh, Lithium battery

So why don't work save parameters in BBR? (Battery Backup registers)

2. What are logic levels for TxD RxD pins?
   From spscification: Interface serial CMOS, 9600 bps, 8N1
   CMOS 5V or CMOS 3.3V
   Is RxD 5V tollerant?
   Are there any buffers between pins and uBloxModule?

Regards
TeleVox