The response to your question is highly dependent on the nature of your contact, the location of your business and your customers, and what you mean by "verify account information." It is not dependent on what you call your center. For the legalities of the situation, you should consult a lawyer and understand laws for your state, and from the FTC and FCC. The laws for "telemarketing" or conducting "telephone solicitation" (see FTC and FCC definitions) govern calling times. You need to determine if your call types fit in those definitions.
Regardless, however, no business should irritate their customers. A call at 7 a.m. local time certainly runs that risk, as evidenced by the "complaints" you have received. For strategic business practices, I think you need to look at who your customers are, and the nature of your contacts, and make a proper business decision. I think a quick survey would tell you 7 a.m. is too early.
You may also want to review the ATA code of ethics.