Called my cell phone. Didn't leave a message. Caller ID shows "Unregistered" and number. Did a little research on this number and this is what I found....
State:    TX
Timezone:    Central
Current time:    3:03pm
Carrier:    Edigen, Inc. - Tx
Type:    Unknown
("Type" meaning landline or wireless) I can tell you the 713 area code is for Houston.