By default pon does not wait around too long to establish a connection. Sometimes it does not wait long enough. You can introduce a longer wait (e.g., two minutes) as below.
Edit /etc/ppp/peers/provider (assuming your connection is the default, called provider) to replace:
connect "/usr/sbin/chat -v -f /etc/chatscripts/provider"
with
connect "/usr/sbin/chat -v -t120 -f /etc/chatscripts/provider"
If you connection is not the default provider but something else, then edit the file with the same name in /etc/ppp/peers/.