Interesting article in the Economist here This Message will self-destruct.."

A growing trend in private and encrypted communications apps between individuals who for whatever reason want to keep things private - sometimes good reasons - but to anyone here it has obvious uses for APs. Messages and pictures can all be deleted quickly and easily, or after a certain time..

So, if you are snooping somebody's smartphone and you see any of these apps on their phone: Wickr, Snapchat and especially Pairs ( designed for couples communications), it is a major red flag!

Thanks for the heads up!

Also, keep check on any smartphones that have been updated to newer phones. These phones have wifi capabilities even after the phone number is gone from them. These give the ability for waywards to use new email accounts, Facebook, chatrooms and dating sites right under your nose under the guise of "playing solitaire".
They feel comfortable doing it, because you think all the mojo got put into the new phone! This can also work to your advantage in that you can wifi an old smartphone and use it for MB and your supersleuth wayward will never pick it up on the keylogger they may have installed. You can get into their facebook and they can't keylog that either. I just did wifi to an old smartphone for radio stations, and FB started going off with messages, updates and all. That phone can do everything except make a phone call. Find the old phones of the waywards to "donate to the troops" check them out, and then donate them to the troops. Once I did a wifi on that phone, it stays on there til i choose to disconnect. I wifi'ed it to my home internet service.

Actually, you can make phone calls over wifi. My wife and I just got back from three weeks in Italy and we used our smart phones (her iPhone, me android) and her iPad to make calls over WiFi using various Google Voice aps and texting over WhatsApp so we didn't pay international roaming charges, etc.

Skype is also available on smart phones, so that's another way someone can call.

Also, if someone hacks and iPod touch, they can use it over wi-fi to make phone calls as the same apps that work on the iPhone and iPad when side-loaded to an iPod touch give the phone call and texting abilities over wi-fi.

So be careful, someone can make phone calls over WiFi with a smart phone.

Overwhelming, just overwhelming!