Openr2 protocol error call trace

[20:24:04:458] [Thread: 3059006352] [Chan 9] - Call started at Mon Sep 22 20:24:04 2014 on chan 9 [openr2 version 1.3.3, revision (release)]
[20:24:04:459] [Thread: 3059006352] [Chan 9] - Initialized R2 MF detector
[20:24:04:459] [Thread: 3059006352] [Chan 9] - CAS Tx >> [SEIZE ACK] 0x0C
[20:24:04:459] [Thread: 3059006352] [Chan 9] - CAS Raw Tx >> 0x0D
[20:24:04:934] [Thread: 3059006352] [Chan 9] - Alarm Raised
[20:27:02:429] [Thread: 3059006352] [Chan 9] - Alarm Cleared
[20:27:02:438] [Thread: 3059006352] [Chan 9] - Bits changed from 0x00 to 0x0C
[20:27:02:438] [Thread: 3059006352] [Chan 9] - CAS Rx << [0x0C] 0x0C
[20:27:02:438] [Thread: 3059006352] [Chan 9] - Protocol error. Reason = Invalid CAS, R2 State = Seize ACK Transmitted, MF state = Seize ACK Transmitted, MF Group = Backward MF init, CAS = 0x0C
DNIS = , ANI = , MF = 0x20
[20:27:02:438] [Thread: 3059006352] [Chan 9] - Attempting to cancel timer timer 0
[20:27:02:438] [Thread: 3059006352] [Chan 9] - Cannot cancel timer 0