Subject: [Megaco] Megaco Vs. MGCP digitmap questions

From: Ramesh Babu Kuppili <[email-masked]>
Date: Fri, 21 Dec 2007 01:43:38 +0530

Hello,
 
I have a question about the difference between MGCP and Megaco Digitmaps.
 
Having read about MGCP digitmap (RFC 3435) and Megaco digitmap (RFC 3525), there are major differences in the way the digitmaps are processed in these two
procotols.  I would like the MGCP/Megaco gurus to confirm if my understanding of the RFC is correct.
 
1.  MGCP requires that an exact match completes the dialing, even if the rule is ambiguous.  For example, a digitmap like (0|00) will match '0' and never get to '00'.  For
            '00' to match the digitmap must be (0T|00). 
    Megaco requires that an exact match to wait if it is ambiguous.  For example, a digitmap like (0|00) will not match and go on '0'.  On the first '0', it starts the inter digit
            timer to see if '00' will be dialed.  In megaco it seems that we cannot have a fast match in the real world.  For example, how would we create a digit map that can
            fast match for 911 and also be able to do seven digit dialing for numbers that start with 912, 921 etc.
 
2. MGCP can only specify T timer.  Megaco can specify S (short timer) and L (Long timer).
 
3. In Megaco given the digitmap (1xx|9xx|0[2-9]xxx|00[1-9]xxxx|[2-8]xxxxxx|0[2-9]xxxxxxx|05xxxxxxxx|x.F|E|F|[0-9].L) and the user dials *26#.  
        My understanding is that we will
        have a unambiguous match as soon as the user dials '*' (asterisk) as the fist digit.  So we send a notify with '*' (asterisk) and clear the dialled digit buffer.  Then
        when the user dials "26#" we have an unambigous match for x.F and we send a notify for 26#.  Please let me know if my understanding is correct.

- ramesh
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