Singular cell phone problem

Could be any number of things....here's the most common causes

https://www.dialpad.com/blog/dropped-calls/

Does it cut in and out when talking to the service supplier as a Customer?

It could be a family related problem?

sorry to say...but it happens.

In my opinion it's the DSP. DSP has taken the quality out of audio. Not just cell phones. Television audio has no enjoyment to it, and requires interaction to get thru a show. Pleasurable tv viewing is long passed.

The only faithful audio now days is in person audio. DSP for audio should be outlawed. With our current speeds and bandwidths, this mutilation should cease.

This is just (pretty dumb) speculation. I wonder if the echo cancelling algorithms are getting "confused" because of similarities in your voices.

If you set up a call then one of you hands his phone to a wife or girlfriend (someone with a very different voice): do they get the same problem?

You could also try calling your brother on someone else's phone: one on the same network as yours, and, one on a different network.

Just trying to narrow the problem to the root cause.

OP here. I read the piece that SolarEagle noted. It suggested removing the SIM card, checking it for damage, then restarting the phone. My SIM looked OK, but I blew it clean anyway. I just now talked with my brother for 1/2 hour and no problems! Perhaps the SIM was not making good contact and reseating it helped? Simple things sometimes. Will post if things change.

That's a head-scratcher for sure! It could be a compatibility issue or perhaps something funky with the network. Have you both tried updating your phones or checking for any software tweaks that might help?

Sometimes those sneaky settings like to play hide and seek. And if you're diving deep into tech mysteries, https://multitechverse.com/ might have some cool insights!