Telus Corp (T.TO), one of Canada's biggest telecom companies, reported a smaller-than-expected profit on Friday, as it spent heavily to win and retain wireless customers by investing in customer service and subsidizing high-end smartphones.

Its shares fell 69 Canadian cents, or 1.5 per cent, to $44.86, making it one of the biggest contributors to the S&P/TSX composite index's decline.

The company reported adjusted earnings of 68 cents per share in the second quarter ended June 30, missing the average forecast of 72 cents of analysts polled by Thomson Reuters I/B/E/S.

Vancouver-based Telus is engaged in a heated battle with rivals BCE Inc (BCE.TO), Rogers Communications Inc (RCIb.TO) and Shaw Communications (SJRb.TO) for wireless customers that has prompted carriers to spend heavily on marketing and customer promotions.

Operating expenses before depreciation and amortization rose by $120 million to $2.08 billion, the company said.

Telus said new postpaid wireless customers rose to 99,000 during the quarter, compared with 61,000 a year earlier. The average monthly wireless bill rose 3.9 per cent to $66.87 as customers streamed more videos online and utilized data-intensive services.

While the wireless performance "crushed all metrics," the additional spending weighed on profit as the company discounted phones and offered other incentives amid heightened competition, Barclays analyst Phillip Huang said in a note to clients.

BCE and Rogers also reported strong growth in wireless subscribers and average bills in the quarter.

Telus is facing renewed competition in western Canada from rival Shaw Communications, a strong player in the region that recently launched new internet and video products.

Telus added 17,000 internet connections and 5,000 television subscribers during the second quarter, slightly lower than what analysts were expecting, as Shaw gained market share, according to Huang.

Net income attributable to Telus shareholders fell to $379 million, or 64 cents per share, from $416 million, or 70 cents per share, a year earlier.

Operating revenue rose to $3.27 billion from $3.15 billion, the company said.