Loss of Cell Connectivity After IOS 16.3 Update- iPhone 13 Pro Max

My daughter has been having this issue intermittently with 16.2 iOS since 2/8. Unknowingly, she upgraded to 16.3 and now her iPhone 13 will not connect to data at all. It went into SOS only mode, and was able to temporarily resolve that; however, after resetting network settings, she has no data connection at all.

My IPhone can no longer make or receive calls. One hour with the customer service at TracFone wireless and then 2 1/2 hours with Apple support. No resolution. Both are blaming the other for the problem which started happening only after upgrading the iPhone SE second generation to IOS 16.3.1, urgent security update.

Happen to my iphone 12 mini, already reset network setting and install new ios from itunes still not working. The sim work fine on other phone. Issue occurred after update ios 16.3 . Sold my phone now using an iphone 11 and will not update.

You should contact your cellular carrier.

Your iPhone SE 2020 does not support the same frequencies as your iPhone 13, especially if the SE 2020 is only connecting at 4G speeds.

The phones support the following frequencies, I've emboldened those unique to the iPhone 13:

iPhone SE 2020:

• 5G NR (Bands n1, n2, n3, n5, n7, n8, n12, n20, n25, n28, n29, n30, n38, n40, n41, n48, n66, n71, n77, n78, n79)
• FDD‑LTE (Bands 1, 2, 3, 4, 5, 7, 8, 12, 13, 14, 17, 18, 19, 20, 25, 26, 28, 29, 30, 32, 66, 71)
• TD‑LTE (Bands 34, 38, 39, 40, 41, 42, 46, 48)
• UMTS/HSPA+/DC‑HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
• GSM/EDGE (850, 900, 1800, 1900 MHz)

iPhone 13:

• 5G NR (Bands n1, n2, n3, n5, n7, n8, n12, n20, n25, n28, n29, n30, n38, n40, n41, n48, n66, n71, n77, n78, n79)
• 5G NR mmWave (Bands n258, n260, n261)
• FDD‑LTE (Bands 1, 2, 3, 4, 5, 7, 8, 11, 12, 13, 14, 17, 18, 19, 20, 21, 25, 26, 28, 29, 30, 32, 66, 71)
• TD‑LTE (Bands 34, 38, 39, 40, 41, 42, 46, 48)
• CDMA EV‑DO Rev. A (800, 1900 MHz)
• UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
• GSM/EDGE (850, 900, 1800, 1900 MHz)

This means if the cell tower tells your iPhone 13 to use one of the frequencies in bold, it could have difficulties that you will never see when using the iPhone SE because it can't access those frequencies.

At the very least your carrier can help you through additional debugging as they can see whether their network can see your phone or not from their side.

If Apple said your phone needs repair, you will need to get it repaired.

If AT&T says there is nothing wrong, ask why they have millions of the same devices running the same software working properly on their network when yours does not.

I'm using iphone 11. After updating ios 16.3 my sim internet connection disconnecting frequently.

Same answer - it's an issue with your cellular provider.

I also have faced same problem and did investigation for 1 and half month and concluded that my phone is unable to get cellular band 900MHz

any one have any idea how can i change cellular band

Actually i am in Maldives and recently the have upgraded their antenna and changed the cellular band 900 MHz and i am able to connect the antenna nearby island coz that antenna is not upgraded

My iPhone 11 Pro will show LTE when in fact it is connected to our WiFi. When the phone “wakes up” is when I notice the LTE designation. Then when I go to an app, it indicates WiFi connection. I have performed all the suggested steps but it’s not our WiFi. All of our other devices are not having WiFi issues. Can’t seem to get this resolved. Wish I could go back to previous iOS version

Greyed-out signal bars do not represent your signal level, they represent your possible signal level with the actual signal level denoted by solid black or white bars, depending upon your screen settings.

For example, this represents three out of four bars of cellular signal, a full scale Wi-Fi signal, and a 99% battery charge (I have the Battery Percentage option enabled):

Your watch doesn't use the exact same cellular frequency bands as your phone.

You don't specify which phone, but:

Apple Watch Ultra:

LTE

• 1 (2100 MHz)
• 2 (1900 MHz)
• 3 (1800 MHz)
• 4 (AWS)
• 5 (850 MHz)
• 6 (850MHz)
• 7 (2600 MHz)
• 12 (700 MHz)
• 13 (700c MHz)
• 14 (700 PS)
• 17 (700b MHz)
• 18 (800 MHz)
• 19 (800 MHz)
• 25 (1900 MHz)
• 26 (800 MHz)
• 39 (TD 1900)
• 40 (TD 2300)
• 41 (TD 2500)
• 66 (AWS-3)

UMTS

• 2100 MHz
• 1900 MHz
• 1700/2100 MHz
• 850 MHz

iPhone 14 Pro Max:

• 5G NR (Bands n1, n2, n3, n5, n7, n8, n12, n14, n20, n25, n26, n28, n29, n30, n38, n40, n41, n48, n53, n66, n70, n71, n77, n78 n79)
• 5G NR mmWave (Bands n258, n260, n261)
• FDD-LTE (Bands 1, 2, 3, 4, 5, 7, 8, 12, 13, 14, 17, 18, 19, 20, 25, 26, 28, 29, 30, 32, 66, 71)
• TD-LTE (Bands 34, 38, 39, 40, 41, 42, 46, 48, 53)
• UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
• GSM/EDGE (850, 900, 1800, 1900 MHz)

So for example if your carrier's cellular tower antennas are not optimized for FDD-LTE band 8, if the tower's base station controller assigns your Apple Watch to LTE band 7 but your iPhone to FDD-LTE band 8, your watch may work perfectly but your phone may report "No Signal."

Why do you believe that?

For example, both the iPhone 14 Pro and Pro Max support GSM/EDGE (850, 900, 1800, and 1900 MHz).

However, the 900 MHz band is not used in the United States, only the 850 MHz and 1900 MHz bands are.

The fact that the incidents were coincident in time does not mean they were in fact, related.

Multiple cellular providers also use the same towers and in fact same networks, so just because you have eSIMs from two different providers does not mean there is not a local issue.