I would advise everyone to NOT call this number until this service is proven to be legitimate.Scammers pretending to offer a support phone number isn't something new.They will probably somehow ask for details about your Bittrex account in order to "help" you and steal your funds from your account.
Be aware.
I second this. The website was reported as phishing by VirusTotal, and the registrant's location is India, Delhi according to WhoIs. Besides, Bittrex exchange doesn't have any support numbers on their page. The 'bittrex support number' he is posting is posted for most other exchanges on multiple phishing sites as well.