HTC Tilt 8900 - Manual (Page 9)

9
Use only the supplied integral antenna. Use of unauthorized or modified
antennas may impair call quality and damage the phone, causing loss of
performance and SAR levels exceeding the recommended limits as well
as result in non-compliance with local regulatory requirements in your
country.
To assure optimal phone performance and ensure human exposure to RF
energy is within the guidelines set forth in the relevant standards, always
use your device only in its normal-use position. Do not touch or hold the
antenna area unnecessarily when placing or receiving a phone call. Contact
with the antenna area may impair call quality and cause your device to
operate at a higher power level than needed. Avoiding contact with the
antenna area when the phone is IN USE optimizes the antenna performance
and the battery life.