 was detected in the BR opportunity selected by the MS or the mobile station's BR preamble sequence was not included in the selected BR opportunity in the BR-ACK A-MAP IE, the MS would consider it as a NACK. On successful decoding of the quick access message, the BS may provide a UL grant to the MS using the STID and the BR index provided in the quick access message. If the MS receives neither a UL grant nor a NACK, it starts the BR timer at the DL frame located immediately after the UL frame in which the MS has sent the BR. If the BR-ACK A-MAP IE indicates successful reception of the BR preamble sequence and quick access message, the BR timer value is set to the Differentiated BR Timer acquired during the DSx procedure. For all other cases, the BR timer value is fixed. The BR timer is stopped on reception of the UL grant. The MS considers the BR attempt as failed and may restart the BR process if either of the following conditions is met: (1) the MS receives a NACK or (2) the BR timer expires. During the three-step BR procedure, if the BS is unable to decode the quick access message, the BS falls back to the five-step BR procedure illustrated in Figure 6-25. In that case, in step 2, the BS provides a UL grant to the MS using a BR-ACK A-MAP IE or CDMA Allocation A-MAP In step 3, the MS transmits a standalone bandwidth request header or uses the assigned UL resource for its uplink data transmission instead of the BW-REQ message. In both cases, STID is carried in the uplink transmission. When using a five-step procedure, the MS starts the BR timer after sending the BR header in step 3. The BR timer value is set to the Differentiated BR Timer acquired during the DSx procedure. The MS stops the BR timer on reception of the UL grant. The BR procedure may restart after expiration of the BR timer. In a five-step random access BR procedure, an MS only sends a BR preamble sequence. If the MS receives neither UL grant nor NACK in the next DL frame following transmission of the BR preamble sequence, a fixed value timer is a