Hi stonechat, welcome to the forum. Yes, there are many SMS app available in the Play Store. You don't mention if your Nexus 7 is wifi only or not but of course if it is wifi only you will need to be connected to wifi to receive the texts. One good option for SMS is Google Voice which allows texting but can also serve as life long telephone number that you can always receive calls and texts on regardless of what type of phone you have (it can even be forwarded to a land line).