Handfull of company phones go straight to voicemail

[BillyLong]

Hello, we have some company phones that are going directly to voicemail when called. The models are S20 FE, A53 5g and A03s. It is completely sporadic, happens with good and bad signal but happens to the individuals at home and at work. DnD is OFF, Call forwarding is OFF there are no relevant blocked numbers. I've tried the network reset feature, have tried with Bluetooth turned OFF and ON. Phones have been restarted multiple times.

[BillyLong]

These same phones will also take about 10 seconds before both sides can hear each other properly when a call does successfully go though.  All phones are new within the last 12 months

[A-B]

Hello. It seems you've already done some great troubleshooting, but a call in to our Mobility team may be in order here. They'll most likely have to refresh some network profiles (basically a reboot on our team's side). It definitely is an odd situation as it happening in multiple locations suggests a hardware or SIM issue, but since there are three different devices, etc. that may be unlikely as well.