Having trouble setting up data calling with rmnet_data0 interface

I'm trying to set up a data call through rmnet_dataX interface which is referring to a cellular connection through the card inserted, but having trouble doing so. I do the following

ifconfig rmnet_data0 up

I then assign an IP statically

rmnet_data0 Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.246.68.132  Mask:255.0.0.0
          UP RUNNING  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

Add the default path in the routing table

ip ro add default via 10.246.68.132 dev rmnet_data0

Add the DNS server

echo "nameserver 8.8.4.4" >> /etc/resolv.conf

Set NAT rules

iptables -t nat -D POSTROUTING -o rmnet_data0 -j MASQUERADE

Routing table

netstat -r 

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

default         10.246.68.132   0.0.0.0         UG        0 0          0 rmnet_data0
10.0.0.0        *               255.0.0.0       U         0 0          0 rmnet_data0
192.168.225.0   *               255.255.255.0   U         0 0          0 bridge0

ping google.com // fails

Also, the default path really just indicates the packets coming to the gateway IP are routed to the external network which in this case is network data? Given that, are NAT rules really required?