This is Smart One Energy. They use caller ID spoofing, which means that the number that shows up on your caller ID is not the number they are calling from. Some of their sales people also say (fraudulently) that they are calling from Washington Gas and that you qualify for a discount on your bill, and that they want to verify your account number. DO NOT give them your account number unless you want to switch gas suppliers. They will take it and switch you from Washington Gas to their company, without your permission.
How did they get your phone number? Washington Gas provides third party companies with your home phone number as part of the new competitive supplier market. You can opt out for one year by calling Washington Gas between 9/1 and 10/13 and asking to enroll in "Opt Out" so that your home phone number will not be shared. You will have to do this every year, however.
301-467-2608 called today and claimed to be Washington Gas offering reduced rates and a discount in what obviously was a scam. The caller had an African accent. If you receive such a call hang up.
I have received two calls from this number. The callers do have thick accents and are difficult to understand, but they represent an actual company called "Smart One Energy" that is an authorized alternative energy provider in Maryland. Their pitch is not appealing and I don't know if their product is worthwhile, but it may be a little hasty to write them off immediately as a "scam."