You didn't specify the situation. That is, if you are using a double sim phone, whether the phone was with you before you picked it up, whether it was ringing, or if you have received the call and heard something.
Now there can be several possibilities depending on the answers to the above said questions.
For example, if it is a double SIM phone, and the phone was not screen locked, and you have your own number saved, it could be that accidentally the number got pressed and the call was made.
But if that was not the case, and you were having the same phone with you and you heard it ringing and could receive it, then it could be that your phone has been hacked or, someone got a fake SIM made with the same number you have. It is most probably a scammer making a robocall for illegal reasons.
Today there is Technology available that makes it easy for the spammers to "spoof" their caller ID information. They are able to make it appear as if they're calling from a certain place or phone number. It can be your own number. It is a trick used by the Scammers to avoid call-blocking and thus dodge their way escaping law enforcement. They do it purposely knowing well that one would be curious to pick it up. If you do, their mission becomes successful, and you would repeatedly getting such calls. So, it is advisable, not to pick or receive such calls.