1. how OBI100 process the calls, starting DigtialMap or OutboundCallRoute? The OBi manual describes the DigitMap as: A digit map serves to transform and restrict the number that may be dialed or called, and determine if sufficient digits have been dialed by the user to form a complete number. Each map is composed of one more rules surrounded by parentheses (which MUST NOT be omitted).
The Obi manual describes the OutboundCallRoute as: It tells the device where to send the call when the endpoint attempts to make a call.
2. how to configure to make it work for 011|00 calls go to gateway3 to match the dialplan for my SPA3000?
The elements in the SPA3K dial plan you refer to are which send a call starting with 00 to @gw1 and which changes a call starting with 011 to 00 and then sends the call to gw1
For the OBi I would put the 011 to 00 transformation in the DigitMap and put the outbound 00 routing in the Outbound Call Route for the Phone Port. If you are using the AA you would also have to put the additions in the Automated Attendant DigitMap and OutboundCallRoute.
DigitMap: add this element OutboundCallRoute i.e. in your DigitMap in your OutboundCallRoute