[Serusers] Problems with DTMF using SER and Asterisk

Hi all, I have a problem getting dtmf tones throgh to PSTN when using asterisk. The connections is SIP phone - Asterisk - SER - Cisco GW - PSTN When dialling PSTN numbers from the SIP phone and pressing the * or # button nothing is happening. I' ve set the dtmfmode=rfc2833 in asterisk. The problem is that to be able to control the asterisk voicemail the dtmfmode has to be =rfc2833, and the I can control the voicemail. But when calling external to PSTN the * and # button is not working. I do also have another problem, and that is when connecting a ATA box to the Asterisk. If I set dtmfmode=inband, voicemail in asterisk can be controlled but not the calls to external PSTN numbers. If I set dtmfmode=rfc2833, voicemail in asterisk do not work, but external calls to PSTN can be controlled with * and #. What can be the error? Please help, Thanks Anders