Legal Question in Employment Law in California

The answer depends on how the contacts were acquired. If anyone can contact them by publicly available means, like opening up a phone book or doing a little research within the trade, there should be no problem. But if you acquired these contacts through your employment, by using information which is uniquely developed or only available through your former employer, they would more likely be considered a trade secret and cannot be used after you leave the employer. There are many factors the go into determining whether customer information is a trade secret, not the least of which is any contracts you may have signed during your employment.

In some cases, it is permissible for an ex-employee to send out announcements to customers they worked with, that they are now in business elsewhere, and leave it up to the customer to decide with whom they choose to do business with.

It is always a good idea to consult with an employment law attorney, with experience dealing with trade secrets, to avoid a costly lawsuit brought by your former employer.