I think these two device use different hardware and software , because wireless gateway V2 we changed the software , for speed up to sending SMS , we not wait SMS report anymore , So the SMS result status not change, If gateway send SMS out , no matter other side get or not it will be sending , If you want to get status you need to get from SMS report .
You can check SMS outbox if sent out SMS status changing or not ? If status changed from sending to delivered, you can try to capture network port from the gateway ..