# Transformations

- Called, calling, and redirecting numbers are different fields.
- A mask can fix or break caller ID.
- Translation patterns change digits and can change the CSS.
- External phone number masks are a presentation tool.
- Write the digits before and after each step.

Most 'wrong caller ID' tickets are a mask on the route pattern, the route list, or the trunk, applied in an order the engineer did not draw. Capture the outgoing INVITE and compare it with the directory number.

Users dial 9 and a national number. The pattern strips the 9 and prefixes the carrier's expected digits. The calling number is masked to the site's main number. If the mask is the directory number instead, the carrier may reject the call.

## Sources and go deeper

Independent, free, learning-only student project.

Opened 2026-10. A row marked confirm has no link, because that page was not verified.

- Cisco. [Cisco Unified Communications Manager product support](https://www.cisco.com/c/en/us/support/unified-communications/unified-communications-manager-callmanager/series.html). last checked 2026-10
- Cisco. [System Configuration Guide for CUCM, Release 15](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15.html). last checked 2026-10
- Cisco. [Cisco Collaboration Preferred Architectures](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/uc_system/design/guides/PAdocs.html). last checked 2026-10
- Cisco. [Preferred Architecture for Cisco Collaboration 15, design overview (PDF)](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/overview/15x/clbpa15x.pdf). last checked 2026-10
- Protocol and ports. [CUCM 15 TCP and UDP port usage](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_m_tcp-and-udp-port-usage-12-0.html). last checked 2026-10
- Protocol and ports. [IANA SIP parameters](https://www.iana.org/assignments/sip-parameters/sip-parameters.xhtml). last checked 2026-10
- Community. [Cisco Community, Collaboration knowledge base](https://community.cisco.com/t5/collaboration-knowledge-base/tkb-p/4691-docs-collaboration-voice-video). last checked 2026-10
- Wikipedia. [Voice over IP (Wikipedia)](https://en.wikipedia.org/wiki/Voice_over_IP). last checked 2026-10
- Wikipedia. [CUCM (Wikipedia disambiguation)](https://en.wikipedia.org/wiki/CUCM). last checked 2026-10
- Cisco. Collaboration 12 SRND book. confirm. The historical Collaboration 12 SRND path opened as a product listing, not the design book. Use the Preferred Architecture index, which was opened. last checked 2026-10
- Wikipedia. English Wikipedia article for Cisco Unified Communications Manager. confirm. That title returned HTTP 404. The CUCM disambiguation page is the Wikipedia page that opened. last checked 2026-10

Room or sheet file: ../../rooms/sources/transformations/sources.json