Fortunately most women are adept at this. Learn to prefer it. I am happiest talking on the phone, bouncing the baby on one hip, and stirring a pot of spaghetti on the stove - something for the heart, the mind, and the hands. I sometimes keyboard while on the phone ('mute' on headset). I can make a grocery list while I talk to someone.
This is predicated on "automatic processing" tasks; not something new to you or that you're not good at.
Practice up on doing two things at once, if you aren't used to it. It exercises both parts of your brain, it allows you to learn and grow, and, if you're a mom, it's making a virtue out of a necessity!
1. Many babies find it soothing if you hold them against your chest and they can hear the sound of your voice as you talk.
Have you tried it?
2. Get a headset!
I'm a coach and use one all the time. Wish I'd had one when the kids were little.
You'll eliminate neck and upper back pain from 'crooking your neck'.
It gives you mobility - on coaching calls, I walk all over the house. I've signed Fed-Ex papers, put away laundry or toiletry items from the store, gone out to the mail box, switched clothes from the washer to the dryer, and rescued the cat. You can grab scissors away, or remove the dog dish before the toddler gets to it.
3. Have something special nearby to entertain your child while you're on the phone. You can keep a box of supplies near the phone, or be creative and improvise.
Keep all the plastic-ware in a low stove drawer, and the aluminum pans in a low cabinet. Just open them up at phone time.
Pull over crayons and paper and color with your child while you talk on the phone. It's soothing.
"Doodle" with your child - just takes a pencil and paper.
With a more active child, roll, kick or throw a ball back and forth. If you're clever you can throw it into another room and it will take longer to retrieve! (Go over the rules during a quiet time - can't be throwing up at the chandelier, etc.)
Make use of food - lay out trails of raisins, goldfish crackers, cheerios, froot loops, pieces of fruit and other tidbits for your toddler. Any surface can become "sanitary" with a piece of aluminum foil waxed paper, paper towel, napkin or clean dish towel laid out and those things are always handy.
Have a special box near the phone of something fun they don't get to play with at other times. Special puzzles, a box of feathers, face painting.
Empty out the utensil canister on the floor - the rubber spatulas and whisks won't hurt or get hurt, and can be an interesting diversion.
Add to the above a supply of those plastic grocery bags you always have around and they can 'put' and 'place'.
Give them a loaf of bread - what does it cost? 79 cents. It's squishy, like play-doh, but easier to clean up. (Watch the plastic bag.)
Special food treats like those juice bags with the straws; something they get only at 'phone time.'
4. Make use of eye contact, 'mouthing' and facial expressions.
Your child will always want to show you what they're doing or playing with and you can raise your eyebrows, open your mouth in surprise, wave with your hand, make the "OK" signal, point your "silencer" fingers at your lips to remind them to be quiet (as best they can), point at things they're asking for and in various ways give them the connection they crave. You can learn to be a regular mime!