AT&T (T) - Get Report was up 8.7% in early trading after Morgan Stanley Dean Witter upgraded it to strong buy from neutral, saying Ma Bell is undervalued by about 75% at current prices. Analyst Simon Flannery said the planned breakup of AT&T into four companies "should unlock substantial value for shareholders." Separately, Internet service provider Excite@Home (ATHM) - Get Report, which is controlled by AT&T, said its broadband subscriber rolls had increased 27.5% in the fourth quarter, within the 25% to 30% range it targeted. Excite@Home was up 8.6%.