Dialtone echo back problem

My asterisk server is connected to PSTN line. When we call to my asterisk server some IVR plays and asked to dial number. Dialing tone plays as we dial in our phone keypad but it also plays echo of that dial tone after some time. Dial tone and echo of that dial tone makes confusion when we dial more numbers in phone keypad.
how can i remove echo ?

i have already tried this

echocancel = yes
echocancelwhenbridged = yes

But no effect.

What technology are you using for the local phone? If VoIP, the phone itself is responsible for echo cancellation in that direction. In any case the remote system should remove dialtone when it recognizes the first digit.

Please use Asterisk Support for future support requests.

Thanks David
we are using Analog PSTN telephone line to connect to asterisk server.There is no any echo problem when we call from VoIP softphone.