My customer has a DN from his telco with 12345-xx. Bud he had configured a DN with 12345-xxy on his old PBX. How can I do this on a 1751 with BRI. I have big trouble, because the gateway try to match the DN after it becomes 12345-xx from telco. This number is to short! It should wait one digit more and than try to match.
You need to make sure you have allowed overlap receiving on the BRI interface and also that the incoming dial-peer has a destination-pattern statement that ends in T.
My guess is that you are in Germany, I've had this problem there before, whereby the incoming gateway was only set to accept the minimum number of digits.