I could have been that person many years ago after I got divorced, having been on the listening end since, I cannot be more grateful to the friend who listened to me for hours on many occasions. In effect it served the place of counselling for me. The other day I found myself falling into that trap with a newish friend and felt mortified after hanging up. I apologised but he said it was fine, and luckily next time he called he was the one who did the talking about a problem he is facing - but I have a sneaky feeling that he did it to make me feel better.
I agree with the suggestion that you find things to do in that situation - put the phone on speaker and get on with anything that doesn't make a noise - even watch cute videos of dogs or cats with no sound, or watch tv with the subtitles on! The friend might get over it in time, but if not, encouraging her to join things will give her more things to talk about.
On the other hand if she is only an acquaintance and you don’t want it to develop into a friendship, think up some excuses to cut her off. For example, you could find a ring tone or alarm on your mobile that you can play and say, sorry, that’s the door, or the timer to say dinner’s ready, or in a gap in her talking say it was lovely speaking to her but you have to go out now ( which you can actually do if you don’t want to lie), or just that you have to go without giving a reason. It is quite possible that she is aware of talking to much and regrets it, but then can’t stop herself next time. If she is on lockdown it could be making her worse.