The telephone number +447537438061 is a genuine HSBC number that is used to send out fraud alerts to customers in the United Kingdom. If you receive a call from this number then you can be confident that it is actually HSBC contacting you. This is confirmed by the Received a Text? page on the HSBC website.
Shortly after this text you will receive another text from HSBC giving you a landline number to call to check if the transaction was made by you or not. If you are in any doubt then visit the HSBC website and call one of their customer service numbers.