Sharmila Mistry, 42, was making a call on her hands free device when she crashed with a Mini Cooper at a busy junction in Leicester.
Her BMW mounted the pavement and into youngsters Oliwier Baczyk, 21 months, and Zofia Tabaka, two.
Prosecutors said that whilst the Mini, which failed to stop at a red light, was also at fault, Miss Mistry was driving over the speed limit for the area, failed to notice the other car and did not brake until it was too late.
The two toddlers, whose parents are Polish, died of their injuries later in the day.
The prosecution said: 'The consequences were devastating and ultimately fatal. The prosecution case is that their deaths resulted from a combination of the driving of Christopher Andrews [in the mini] and Sharmila Mistry.'
Zofia's father also gave evidence as he told the court he saw his daughter in her push chair with 'her little head bowed' and blood coming down her face.
He added that he was screaming and shouting for help and that the other child, Oliwier was on the ground in a 'pool of blood.'
Another witness at the scene said that Ms Mistry's car sped past him just before the incident, as he was slowing for an amber light. He told the court that the defendant was 'going too fast.'