Setting up a new iPhone can be an exciting process. You get to pick between either carrying your data over from your previous device or starting fresh to avoid any clutter. Though many consider social media platforms like Instagram as essential firsts, let's not forget the one thing the phone was invented for -- taking and placing voice calls and exchanging texts. Instant messaging apps like Messenger and its alternatives also allow you to make voice and video calls, but a more reliable and universal approach involves using a SIM card.

Newer iPhones now support eSIM, but there are still regions where physical SIM cards remain the standard. You can also deploy a dual-SIM setup -- either by registering two eSIMs, or using one physical card and one eSIM. Regardless of which route you pick, you should see cell service pop up fairly quickly after you insert your SIM card into your iPhone. Spotting a "No SIM Available" or "Invalid SIM" error message can be annoying, but Apple has a few recommended troubleshooting steps you can undertake before contacting your carrier's support team.

First, if you're using a physical SIM card, eject it and check for any visible damage. Any scuff marks, chips, or bends may have rendered the SIM card non-functional -- in which case, you will need a replacement. A good way to test if your SIM card is the one causing you trouble is to insert it into a different phone and see if you can make phone calls.