No, you cannot call a Glasgow telephone number using their 0141 area code for free if you are an O2 customer. However you can avoid paying a monetary charge if you have inclusive minutes remaining on your monthly tariff, regardless of which mobile network operator you are with.
O2 call costs – 0141 telephone numbers
Inclusive minutes that are remaining on your O2 monthly contract or Pay & Go rewards bundle can be used to call Glasgow 0141 numbers for no extra charge, making them essentially free to call. However if you have run out of minutes you will have to pay a minimum charge of 60p for pay as you go customer or 70p if you are on a monthly contract, plus a per-minute rate for each subsequent minute.
Glasgow districts using the 0141 area code