LE confirmed that SC made a phone call to her Cousin T at 5:30 on Wednesday evening. Cousin T said she never received a call from SC as to whether SC was going to spend the night at Cousin T's or not. It seems to me that the call was made but not connected.
I know there has been some confusion over this because of something a podcast moderator said, but the last confirmed outgoing call from Sandra's line before her disappearance was on Tuesday when she last called her daughter. She apparently didn't call anyone on Wednesday, although her cousin did call and speak with her when the boys were still in the house, so before she'd left for the mechanic's.