To the best of my knowledge, REFERENCES are provided by candidates to enhance their chances of recruitment. If you need to know anything about the candidate you can have the verification done. It is candidate’s responsibility to inform the REFERENCES in advance so that they are aware of it and also the context.
Now if I have understood you correctly, you have a data base of REFERENCES with you and you are going to ask the REFERENCES if they wish to have any change in their profile. This is a very delicate situation. It should not become another unwanted commercial call.
As you know the REFERENCES gave their particulars for a specific purpose as explained.
What if a REFERENCE retorts? If some asks from where you got the contact particulars will you tell the truth? You must know how to respect their privacy. Instead of calling you can send a small mail very courteously made. It can still have repercussions if the REFERENCE has no inclination to your proposal / inquiry.