I'm currently on reserve and as Zap said... no long calls. You have 2 hours from notification to be at the airport... essentially 3 hours to push.

As FLY mentioned, it is kind of a second class citizen assignment for a number of reasons. For example, you don't have any trip ownership. If someone wants the reserve trip that you were assigned, they can just take it from you, and you're back on reserve. Also, they'll use you up to your guarantee, and then stop using you. Assuming you haven't picked up any additional flying, and you've flown productive trips on reserve and reached your monthly guarantee, you will be sitting the rest of your available days for free unless you're used. It's explained in detail here: https://swreservepilot.dreamwidth.org/384.html

Now, it's not all bad. For example, unlike at other major airlines, reserves at Southwest fly... A LOT. You're far more likely to fly than sit on the ground... and if you're a commuter, that means less time at crashpad or hotel. You can also give away your reserve blocks. I've had 3-day block taken from me, I've also had people calling me offering to take my 1-day reserve from me before my trip got rerouted/extended. This can work in your favor. Lots of good gouge on that blog...

One last thing, lots of hiring going on. Chances are you won't be on reserve for very long, and if you live in domicile, it's a completely different gig than if you're a commuter.