System Extension Numbers
A few ranges of extensions have been reserved for system use only.
311-911: Services
Please see our article on these extensions.
5000-5999: Application Specific
| Range | Usage |
| 5000-5001 | Voicemail access |
| 5002-5009 | Reserved for future use |
| 5010-5099 | General mailbox |
| 5100 | Reserved for future Use |
| 5101-5110 | Dynamic call parking |
| 5111-5149 | PSTN forwarding |
| 5150-5199 | Reserved for future use |
| 5200-5299 | Queues |
| 5300-5399 | Auto attendants |
| 5400-5499 | Hot desking |
| 5500-5519 | Special application time controls |
| 5520-5529 | Courtesy Phones |
| 5530-5554 | Reserved for future use |
| 5555-5559 | Reporting user |
| 5599 | Teams Connector user (new from June 2023) |
| 5560-5598 | Reserved for future use |
| 5600-5699 | Shared line appearances |
| 5700-5799 | Conference bridges |
| 5800 | SIP page all |
| 5801-5820 | Static Parking |
| 5821-5899 | Reserved for future use |
| 5900-5999 | SIP integrations and custom features |