Duplicated Digit 9 DTMF Relay/ Origination from O2 Germany

Hi there,
I am facing problems with DTMF relay when Digit 9 is pressed. I am using rfc2833 , all digits are relayed properly except the digit 9
9 is mostly doubled and sometimes three times. I have tested it many times and noticed that whenever digit 9 is entered its relayed twice or thrice.
actually at times its relayed properly too. but most of the times its duplicated
The call scenerio is like this: I have hired DID numbers from 3U Germany.
When I call the DID using my PSTN phone (DTAG) or using my T-Mobile or Vodafon or E-Plus mobiles, I have no problems. But when i use an O2 Germany Mobile to dial the did i face this problem.
Strange is that at times 9 is passed correctly but most of the times its duplicated.

Attaching the debug report.

I thought it could be asterisk issue because I saw something like “DTMF end ‘9’ has duration 40 but want minimum 80â€