Alcatel Unleashed

Is it possible to use a 5 digits numbering plan on my clients OXO?

The client wants to interconnect with the PBX at the Headoffice and 5 digits is conisdered required.

Thanks

Dialing plan can be upto 8 digits, but base only 4 digits.
f.e. you can manage 10000 (start) 10099 (end) base 100.