However, shares of OnMobile Global (up 1.33 per cent), Idea Cellular (up 0.90 per cent), ITI (up 0.35 per cent) and Sterlite Technologies (up 0.14 per cent) were trading in green.
The BSE Telecom index was trading at 1462, down 11 points, or 0.73 per cent around 11.20 am (IST).
Notably, the index had hit its all-time high of 1488.27 on Tuesday, 25 July.
Indian telecom sector has seen a major disruption after Reliance Jio made its entry in September 2016. Incumbent operators, such as Bharti Airtel, Vodafone and Idea Cellular have been grappling with the issue of falling revenue since then.
The overall market sentiment remained bullish after hitting an all-time high.
Nifty50 and Sensex hit all-time high at 10,106.80 and 32661.39, respectively.
Barring telecom, all sectoral indices were in green on BSE.
NSE too had all sectoral indices in green.
Nifty50 index was 86 points up at 10,106, while the 30-share Sensex was 276 points up at 32,658 around 11.20 am (IST).
In the Nifty50 pack, 42 stocks were trading positive, while 9 stocks were slipping.
On BSE, 1,228 stocks were advancing whereas 1,065 stocks were lagging.