I'm sorry I'm just still worried...the calls would sometimes ring normally (for 21-24 seconds before going to voicemail) even if his "do not disturb" settings were set to send phones calls directly to voicemail ALWAYS. Can this happen sometimes? Is it due to cell service or towers??
As I said, it sounds to me as if what you're experiencing is normal.
Either you trust your partner or you don't.
The call will go directly to voicemail without ringing if the phone is turned off or in airplane mode. If I call my phone when it's on DND from another phone, it does ring before going to VM.
I'd suggest not overthinking this. As far as I can tell, what you're seeing is normal. It is possible, though, that, sometimes, your boyfriend doesn't want to talk, maybe not to anyone, maybe not to you. If you're wise, you'll let him have that space. If he feels that you would be angry about that, yes, he might lie to avoid having an argument. Not the wisest strategy ever, I agree, but some people do silly things to keep the peace and/or avoid hurting people.
"Do Not Disturb" voicemail problems