The phone rings.
I answer it. It's my friend Dave.
I decide that I'm going to keep talking/continue the conversation with Dave.
I say to my friend, Sue, who is in the room waiting for me to share a meal with her "Sorry, I won't be long. I need to take this call".
I then talk to Dave on the phone for 20 minutes.
I hang up.
I apologise to Sue again for taking the call and talking for so long while she was waiting for us to eat together, but that it was an important call.
To take/taking a call means to take part in a telephone conversation with someone who rang you. It doesn't work if you make the call.
If Dave had phoned and I was too busy to talk to him, I could have said "I'm really sorry. I can't take your call at the moment. I'm busy with Sue".