if you place something similar to the following in as the control source for a text box, and then use that concatenated control source to put into your idfield in table Something it should help.
=[List1].column(x) & [List2].column(y) & [Text1]
In this case List1 and List2 are your list boxes, and colums x and y are the various columns that may be used for example ina multicolumn list box. The column numbers may/may not be the same - it doesn't matter, and Text1 is your text box with its contents.
Note the placement of and difference between the  and ().
You will use the appropriate names for the controls on your form. For example if your first listbox field is named 'phonenum' and your second listbox field is called 'firstname' then the control source will be: