A method of providing enhanced contact information on a mobile communication device, comprising the steps: displaying a user interface screen of an emailing application on a display screen of the mobile communication device, the user interface screen including a contact input field; receiving input via the contact input field; determining a location of the mobile communication device; determining whether a contact name in an address book stored in a memory of the mobile communication device matches the input in the contact input field; determining over a wireless data network whether a contact name in a remote contact source matches the input in the contact input field, wherein the remote contact source comprises a reverse lookup directory service; displaying one or more contact names which match the input in the user interface screen; wherein the location of the mobile communication device is used in combination with the input in the contact input field as a filter in determining whether a contact name in the remote contact source matches the input in the contact input field; wherein the user interface screen is an email composition user interface screen and the contact input field is an address field of the email composition user interface screen; and wherein the step of determining whether a contact name in the remote contact source matches the input in the contact input field is performed automatically; wherein received contact information comprises an indication of whether the received contact information originates from the address book, or a contact database of the reverse lookup directory service, and wherein the indication is displayed in the user interface screen with the respective contact names; wherein the step of determining over a wireless data network further comprises the steps of: instructing the reverse lookup directory service to search the contact database for contact names matching the input in the contact input field; and receiving from the reverse lookup directory service contact information comprising at least a contact name matching input in the contact input field. displaying a user interface screen of an emailing application on a display screen of the mobile communication device, the user interface screen including a contact input field; receiving input via the contact input field; determining a location of the mobile communication device; determining whether a contact name in an address book stored in a memory of the mobile communication device matches the input in the contact input field; determining over a wireless data network whether a contact name in a remote contact source matches the input in the contact input field, wherein the remote contact source comprises a reverse lookup directory service; displaying one or more contact names which match the input in the user interface screen; wherein the location of the mobile communication device is used in combination with the input in the contact input field as a filter in determining whether a contact name in the remote contact source matches the input in the contact input field; wherein the user interface screen is an email composition user interface screen and the contact input field is an address field of the email composition user interface screen; and wherein the step of determining whether a contact name in the remote contact source matches the input in the contact input field is performed automatically; wherein received contact information comprises an indication of whether the received contact information originates from the address book, or a contact database of the reverse lookup directory service, and wherein the indication is displayed in the user interface screen with the respective contact names; wherein the step of determining over a wireless data network further comprises the steps of: instructing the reverse lookup directory service to search the contact database for contact names matching the input in the contact input field; and receiving from the reverse lookup directory service contact information comprising at least a contact name matching input in the contact input field. instructing the reverse lookup directory service to search the contact database for contact names matching the input in the contact input field; and receiving from the reverse lookup directory service contact information comprising at least a contact name matching input in the contact input field.