Q: My iPhone XS, now 26 months old, often doesn’t ring or vibrate when I receive a call. So, unless I’m looking at the screen when the call arrives, I miss it. But this doesn’t happen on every call.

A Verizon tech called me once and the phone rang, then he called me again and it didn’t ring. The tech said he’d never seen anything like it. The only thing that temporarily solves the problem is to change ringtones, and that fix only lasts for one or two calls.

I’ve tried the obvious solutions, such as making sure the ring/silent switch on the side of the phone is turned on, and that no one is blocked from calling. What can I do?

—Richard Borson, McGregor, Minn.

A: There are a few changes to the settings you can try. If they don’t work, you may need to have the phone repaired or replaced. But first, try:

• If you have installed any new apps lately, uninstall them to see if they have been interfering with your ringing.

• Make sure the phone isn’t stuck in headphone mode. If it is, the ringtone may be being “sent” to headphones or external speakers that aren’t connected to the phone.

• Turn off “Do not disturb mode.” It keeps calls from ringing your phone unless the caller has been added to an exception list. Go to Settings, click Do Not Disturb and make sure the top button is off.

• Listen to your ringtone to rule out sound file corruption. In Settings, click “Sounds & Haptics,” then “Ringtone” and then the selected tone. Also check any custom ringtones you use for different callers.

• Check to see if the phone’s speaker needs repair. Open Settings and select “Sounds & Haptics.” On the sliding “ringer and alerts” control, slide the button back and forth several times. Just touching the button should make your standard ring tone play, and by dragging it back and forth you should make the sound softer and louder. If you don’t hear any sound, or if the button on the control is dim, your phone’s speaker may not be working properly.

If none of the above help you, the phone may be damaged in ways you need expert help to solve. You are beyond the one-year warranty that came with the phone. But you may have repair/replacement coverage if you have purchased an “AppleCare+” extended warranty, or if you bought a Verizon insurance plan. For the best Verizon Wireless technical advice, consult a corporate store rather than an “authorized retailer” (search Google for “Verizon corporate store” near you.

Contact Steve Alexander at steve.j.alexander@gmail.com. Include a full name, city and phone number.