Delay to ANSWER channel i TDM400

In case a call comes to TDM400 board it is waits ~ 2…3sec brfore it is answered. Why?! I would like to pick up channel call right away. For instance other calls wich comes from SIP VoIP devese (GSM gateway) answers by same dialplane (extensions.conf) right away.
Do any one can help me to set up Asterisk to answer ZAPTEL channel right away?! PLEEEAS !!!