Have a look at the "Local Dial Plan" under Basic Settings/Preferences.
Extract from the admin guide (pg 5-68)
Available symbols that can be used in the local dial plan are as follows:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9 - Digit symbol
X - Match any digit symbol (wildcard)
*, #, . - Other keypad symbol
| Expression inclusive OR
Dial Plan Example
An example of a SIP Local Dial Plan is:
[01]XXX|[2-8]XXXX|91XXXXXX
XXXX|X+.|*XX
The dial plan in the above example can accept any 4-digit dial strings that begin with a '0' or
'1', any 5-digit dial strings that begin with a '2' up to '8', any 12-digit dial strings that begin with
'91', any non-empty digit string that ends with a '.' or any 2-digit code that begins with a '*'.
LOCAL DIAL PLAN AND PATTERN MATCHING
The IP Phones support local dial plan dialing using pattern matching (i.e. once a user enters a
set of numbers that matches a pattern defined in the local dial plan, the phone will automatically
dial out the number without the user having to press the Dial softkey).
I would think for extensions that start with 3xx you could use the following.
3XX|XX+|*XX
Extension number should dial immediately on match and other numbers will wait for the timeout or until you press the right arrow.
If you have a number plan you could define this even further.
