There are several discussions about this on the forums already. Yes, it's a valid Telus number. Yes, there are scammers that spoof the caller ID data to show that number to try trick people into giving them information. The +1 at the beginning is an easy way to spot it as a scam.
If you are a Telus or Koodo customer, you can enable Call Control (free) and can filter out those calls.
A lady with a strong Asian accent phoned me from this number TELUS 1-888-811-2323. Said she was phoning from Telus but could not verify my address on the account. Asked if I wanted to be listed in the directory with 1) Full address 2) Partial (street name) 3) Just the City 4) Other. I asked her if she could give more info about my account. Her answer was that she could not give this to me for privacy reasons.... I asked her for the number of Telus and to give Telus a call myself. She gave me a this number: 310-2255... I believe this is a SCAM and should be reported as such.