Combining 2 temp tables to aggregate into a single table
Seems to me like you need a JOIN instead of a UNION:

SELECT  ISNULL(T1.[user],T2.[user]) [user],
        ISNULL(T1.TotCall,0) TotCall,
        ISNULL(T2.[120Calls],0) [120Calls]
FROM #tmpTotCalls T1
FULL JOIN #tmp120s T2
      ON T1.[user] = T2.[user]
;