Yes, this can be accomplished.
It took me a little bit to figure it out, but here's how it works. I have a MICS 5.0 system with DID's setup on a T1. I created a route which points to the primary outgoing line pool (Pool A). (Note: external forwarding only works through routes) When forwarding calls, I simply use Feature 4, or [Call FWD} button + 95035551212 + [OK].
NOTE: When forwarding calls from a DID number to another external number, e.g. Cell phone, you are utilizing two channels for the duration of the call. Also, you may experience audio delays, and echos depending on where the call originates from.
Setup:
1. You need to setup a route in [Services] [Routing Services] which points to your primary line pool (Pool A).
By Default Route 000 is setup like this on all service schedules.
2. Assign (Add) a destination code 9 to that route. [Services] [Routing Services] [Dest. Codes]
(IMPORTANT NOTE: if you have 9 setup as a line pool "Access Code" under [system programming] [Access Codes], clear it from that section prior to setting up the new route.)
3. Under [Terminals/Sets]DN#[Capabilities] Set Allow Redirect = Y
4. Go to the set you wish to forward calls from, Press Feature 4, or Call FWD button, enter the destination code + the telephone number you wish to forward to and press the OK soft key.. For example, [Call FWD] + 9 + 5035551212 + [OK].
Let me know if this works.