How to kill in-band DTMF

We are Running Asterisk 1.4.18. The provider sends us via SIP both inband and out of dband DTMF and can not change their settings. We tried to set * to in-band only, but the DTMF seems unreliable (Digits double). So it seems like we need to somehow kill inband DTMF so that it is deleted from the audio stream. Can someone help us ?

DTMF settings are also made at the SIP endpoint. The phone or softphone would have to be changed to prevent in-band DTMF.

IT is a differrent setup. here it is :

We are connected to a mobile provider over sip. Asterisk is connected to our calling card system over E1. So a mobile subscriber calls our number, the call arrives over sip to ASterisk and is then routed to our calling card system over E1.

The subscriber hears an invitation to enter their pin-code.

Here at this point we receive DTMF from the mobile provider both in-band and RFC. Their edges do not alway coincide, moreover, they sometimes arriver intermittently. When we switch off out of band DTMF, then we receive in-band , which soemtimes makes digits double. So we need to receive only out of band DTMF, while removing in-band from teh audio stream, not allowing it to pass over E1

IT is a differrent setup. here it is :

We are connected to a mobile provider over sip. Asterisk is connected to our calling card system over E1. So a mobile subscriber calls our number, the call arrives over sip to ASterisk and is then routed to our calling card system over E1.

The subscriber hears an invitation to enter their pin-code.

Here at this point we receive DTMF from the mobile provider both in-band and RFC. Their edges do not alway coincide, moreover, they sometimes arriver intermittently. When we switch off out of band DTMF, then we receive in-band , which soemtimes makes digits double. So we need to receive only out of band DTMF, while removing in-band from teh audio stream, not allowing it to pass over E1

IT is a differrent setup. here it is :

We are connected to a mobile provider over sip. Asterisk is connected to our calling card system over E1. So a mobile subscriber calls our number, the call arrives over sip to ASterisk and is then routed to our calling card system over E1.

The subscriber hears an invitation to enter their pin-code.

Here at this point we receive DTMF from the mobile provider both in-band and RFC. Their edges do not alway coincide, moreover, they sometimes arriver intermittently. When we switch off out of band DTMF, then we receive in-band , which soemtimes makes digits double. So we need to receive only out of band DTMF, while removing in-band from teh audio stream, not allowing it to pass over E1