A much used digit map for GV is:
Service Providers -> ITSP Profile A -> General -> DigitMap:
(1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|<1aaa>[2-9]xxxxxxS4|011xx.)
Replace aaa with your local code.
The S4 puts in a 4 second delay after dialling seven digits just in case you intended dialling ten digits and you are a slow button pusher.
In most case I prefer that 911 is kept out of digit maps and is sent direct to the intended service provider. You can do this in the Phone Port OutboundCallRoute such as:
{911:sp2},{([1-9]x?*(Mpli)):pp},{(<#:>):ph2},{**0:aa},{***:aa2},{(<**1:>(Msp1)):sp1},{(<**2:>(Msp2)):sp2},{(<**3:>(Msp3)):sp3},{(<**4:>(Msp4)):sp4},{(<**9:>(Mpp)):pp},{(Mpli):pli}
Some users like this method for other numbers too, but I prefer to put those in the digit maps. There's a lot of personal preferences in digit map design. Ask three users here and you will probably get three different answers
The ObiDeviceAdminGuide has some of the answers:
http://www.obihai.com/docs/OBiDeviceAdminGuide.pdfPage 183 onwards deals with digit maps and "Matching Against Multiple Rules in Digit Map". That gets quite deep, but it does tell you how to get them digits sent out as fast as possible!
This forum has some good descriptions of how it all works. The Master Digit Map Guru was RonR - it's well worth searching for posts by him.