UPDATE 1-Adtran shares up on strong quarterly results

* Q2 EPS $0.44 vs est $0.35

* Sees Q3 sales flat to slightly above Q2 levels

* Soleil upgrades stock to buy (Recasts; adds details from conference call, updates share movement)

July 14 (Reuters) - Shares of Adtran Inc ADTN.O touched a four-year high on Wednesday, a day after the network and communications equipment manufacturer posted a quarterly profit that beat analysts' estimates by a large margin.

For the third quarter, Adtran expects revenue to be flat to slightly higher than second-quarter revenue of $150.4 million. It expects third-quarter operating expenses to be slightly up on a sequential basis.

On Tuesday, the company said its second-quarter performance was helped by strong demand for high speed connectivity coupled with increasing demand for ethernet services.

The company said it saw growth across all of its carrier segments and enterprise channels. Its broadband access category grew 43 percent and its internetworking category grew 37 percent.

AT&T Inc T.N contributed 17 percent to the company's total revenue, while Verizon Communications Inc VZ.N and Qwest Communications International Inc Q.N accounted for 12 percent and 20 percent, respectively, Adtran said on a conference call with analysts on Wednesday.

For the second quarter, the company posted net income of $27.8 million or 44 cents a share, compared to $18.8 million, or 30 cents a share in the year-ago quarter.

Analysts were expecting a profit of 35 cents a share, on revenue of $137.9 million, according to Thomson Reuters I/B/E/S.

Shares of Adtran were up 8 percent at $31.14 Wednesday morning on Nasdaq. It had touched a high of $31.38 earlier in the day. (Reporting by Jennifer Robin Raj in Bangalore; Editing by Aradhana Aravindan, Anne Pallivathuckal)