Try this: Create two connections in the connection manager. The first leave empty, i.e. NO modem settings whatsoever.
To do this, go to Connections from the Connections menu in Settings.
Click on the Advanced tab, then choose the Select Networks button.
In the first entry that reaRAB, "Internet connect using", select New. The default name is My ISP Settings. I suggest you change the name (I call mine WiFi). Then select OK. NO SETTINGS ARE NEEDED for this connection!
In the second entry that reaRAB, "private network using", use the Cricket WAP settings. (I call mine Cricket WAP.)
What this will do is try to connect your device to the Internet first using any open available connection. If it can't connect, it will then proceed to dial #777 if your Cricket WAP settings are in effect. Be advised that it will try to dial a connection if it can't find a web page (i.e., page does not exist or has been typed-in wrong).
Good hunting!