Does anyone know how many extensions are possible using 5 digits? SRND for CUCM 5x states (under Dial Plan), 4 digit dialing can yield up to 10000 extensions. No mention of 5 digit. Any help is appreciated.
Not to contradict my fried Rob :)
You have to subtract leading digits that can't be used. eg:
0 is operator and other place is external line
1 is emergency and so in many places
2-8 are generally useable
9 is external line or emergency somewhere
There are other issues that I won't mention for when you have multiple site and want uniform dialing.
All in all, deciding extension length an pattern is not very difficult, but not trivial either.