Hurricane Harvey has knocked out a lot of the regular communications infrastructure in parts of Texas, but a walkie talkie-like app has emerged to fill the need.

The catastrophic events caused by Hurricane Harvey put smartphones to the test, raising the question about what our trusty mobile companions can do to help in crises like these.

After all, we rely on these pocket-sized supercomputers for much of our lives, in a normal state, so surely they can be useful during natural disasters, among other grave situations one might find themselves in.

Your survival plan should include your smartphone, and there are a few things you can do in advance for emergency preparedness, but you won’t be able to rely on your mobile device for everything.

Some thoughts, tips, and tricks to consider for the future:

Cell service not a given

According to the Federal Communications Commission (FCC), only 4% of the nearly 7,800 cell sites in Harvey’s path were knocked out, affecting nearly 150,000 people. By comparison, more than 1,000 cell sites were inoperable during Hurricane Katrina in 2005, leaving millions without connectivity. In other words, communications networks are getting better at weathering major natural events like hurricanes. It’s not perfect – residents in Rockport, Texas, suffered the biggest outage last week, and therefore you can’t assume you’ll have service in these situations.

Call 9-1-1 without a plan

Presuming there is cellular service, people are encouraged to send text messages and emails and posts notifications to Facebook and Twitter about their whereabouts and immediate needs, or to look up where local shelters are. If your smartphone doesn’t have coverage in the area you’re in during an emergency, or you don’t have an active cell plan, you can still reach 9-1-1 from your mobile phone. You can also text 9-1-1, perhaps if you’re unable to talk or need to be silent (perhaps in a terrorist…