Carrier · Number planning
Plan DID blocks for a multi-site org: per-site block size, pilot numbers, department ranges, reception hunt, and CUCM translation patterns. Outputs the exact CUCM entries you need.
Good DID planning keeps expansion cheap. Bad planning means buying 80 DIDs when you needed 10, or running out of 100-block because you didn't leave headroom. This tool sizes blocks, lays out pilots, and drops the CUCM translation plan.
Blocks are sized to users × headroom, rounded up to 10. Extensions match the last N digits of each DID. CUCM translation patterns strip the NPA-NXX and leave the extension — standard inbound scheme for multi-site.
Keep blocks aligned on 10-number or 100-number boundaries so carriers can port cleanly. Never fragment a block across carriers — you'll regret it for years. Reserve at least 5 numbers for pilots (main, fax, AA, VM access, emergency).
Sometimes, for small sites. But carrier 911 routing prefers distinct blocks per physical location.
Reserve 5% of the block (minimum 5) for temps, conferences, growth.
Each site needs ~60 DIDs (40 × 1.5). Block sizes 60 rounded up to a clean 100-block per site — 300 DIDs total. Pilot 2125558000 main, 8001 reception, 8002 AA, 8009 VM pilot.
Block size 300. Pilot 2125558000. Extensions 80001-80299.