Class Snap

Class Snap

Monday, March 31, 2014

Understanding Gatekeepers, Gatekeeper Call Routing & CUBE - Part 2.3/3

Now what happens if a tech-prefix is found by the gatekeeper for an incoming call but the GK is not able to match the remainder of the number to a zone-prefix (let’s say no zone-prefix is configured)... so in this case the GK would not know what zone that incoming call/called number belongs to but instead of dropping the call it would set the target zone = local zone and then look up to see if the local zone is a local or remote zone and then with a valid tech-prefix match earlier would route that call over.... however you could configure the gatekeeper to just drop calls that do not have a zone-prefix match by issuing the command “arq-reject-unknown-prefix” 
Now again, what happens if neither a tech-prefix or a zone-prefix is found, then if the called number is an E.164 number registered to the gatekeeper (E.164 numbers are efxs ports or fxs ports on the endpoint, so when the endpoint registers to the gatekeeper even the directory numbers configured on the efxs (ephone-dn) and fxs ports (number) register to the gatekeeper).... so if neither tech-prefix nor zone-prefix matches then if the called number is an E.164 the gatekeeper sends the call to it.... 

Again, what happens if neither a tech-prefix, zone-prefix nor an E.164 matches... the GK then finally looks to see if a “default-tech-prefix” is configured.... something like the default route... the defaul-tech-prefix would set the tech-prefix to one of the tech-prefixes of one of the endpoints registered to it... and the gatekeeper would then hop that call off to that endpoint... 


So RULE OF THUMB or RULES of THUMB or RULES OF THUMBS or RULE of THUMBS: 

“ A call cannot be routed by the gatekeeper if the gatekeeper does not find a tech-prefix unless the called number matches a registered E.164 number on the gatekeeper…. PERIOD” 
“A Call can still be routed by the gatekeeper if a zone-prefix is not there as it sets the target zone=local zone” 

Endpoints and Gatekeepers speak the language of “A”, “A stands for Affection” …. They speak the language of ARQ, ACF, ARJ (Admission Request is when the endpoint requests the GK to admit a call, ACF is when the Gatekeeper locates an endpoint to send the call to and sends back an ACF to the EndPoint that initiated the ARQ and ARJ is if the Gatekeeper did not find an endpoint to send the call out to in which case it returns the endpoint that initially send the ARQ an ARJ) 

Gatekeepers between themselves speak the language of “L”, “L stands for Love”…. They speak the language of LRQ, LCF and LRJ (Location Request is when one GK sends the other GK a request to admit a call to the remote zone of the other GK and the LCF and LRJ are obvious…) 

The best way to memorize the steps the Gatekeeper takes in its call routing decision process is to mug up the “GK Address Resolution on ARQ” flow chart I specified at the beginning of this doc… this document also has 3 scenarios that test your knowledge and understanding of the GK call routing process… get those 3 right and ur ready to go….

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