How can I stop my toddler form acting out whenever I'm on the phone?

Phone toys. We kept a small basket of fun toys that only came down when the phone rang (including a toy phone). Also, taught toddler to silently place his hand on mine if he needed attention during the call and would get to him asap. Acting out wouldn't get attention, so he learned fairly quickly.
Ignore. I recommend ignoring the behavior and walking away from him ( assuming you wouldn't be leaving him in an unsafe place).
A new TipTap. Ignore him, or conversely - allow him to answer his own "phone" when you are on the phone.