Around 2 a.m., I woke up to what appeared to be an incoming call from my girlfriend. I answered, but the call immediately went to voicemail. The call screen seemed stuck, so I waited for it to end and then called her back several times and sent texts, but there was no response. The incoming call also didn't appear in my phone's call history. The next morning, she said she had been asleep and had no record of calling me—only my outgoing calls appeared on her phone. My provider couldn't verify the incoming call either. What could explain a call that appeared on my phone but apparently never happened?
4 Answers
For peace of mind, check the phone for suspicious apps, update your operating system, and change important passwords if anything else seems unusual. A factory reset is probably unnecessary based on one unexplained call, but it could be considered if other strange behavior continues.
Phones and VoIP services can occasionally produce phantom rings or display a call that never properly connected. If the provider has no record and neither phone shows the call afterward, a software or network glitch is plausible. Restarting the phone and installing updates would be a reasonable first step.
You may have been partly asleep or experiencing a false awakening. Those can feel completely real, including hearing a ringtone and interacting with a phone, while small details—like the call not working properly or not appearing in the history—are off. Sleep deprivation can make this more likely.
It could have been caller ID spoofing. Caller ID information can be faked, so the number displayed on your phone may not have actually been your girlfriend’s. That said, a spoofed call normally still leaves some kind of call record, so this isn’t the only possibility.

I’m fairly sure I watched the phone the entire time, but this explanation is still more reassuring than assuming something much stranger happened. I’ll try recording the screen if it happens again.