Hi Freddie,
Some questions for you......
How big is your system?
You said it's a closed number plan.....does that mean you currently do not have direct dial extensions, if so, when you convert, are you keeping that configuration or are you changing over to a direct dial environment as well?
Are you changing to a 5 digit dial plan because you need to expand your extension capacity, or because 5 digits are what the service provider will be sending you?
Is your conversion such that your existing number ranges will simply be appended with one additional digit, or do you have to transition to a completely different number range?
Can your new number range (whether completely different or one digit off) be added to number analysis without conflicting with existing entries?
We converted our switch several years ago in order to gain more extension capacity (BC6.32). We had direct dial ranges in 2 different office codes and we simply (in term only) appended the 4 digit ext. with the last digit od if's corresponding office code.
However, the actual process was not very simple in that we had 7500 extensions at the time.....Ericsson did a datagen and we reloaded the switch with the converted data -- very similar to a normal system upgrade.
As you plan, try to keep things as simple and logical as possible - this is a situation that is entirely too easy to overcomplicate.
Good luck,
Dave Strang