In an Avaya Aura® environment where calls are routed via Session Manager, the Session Manager is the central point for SIP signaling policy and routing. The most appropriate and architecturally sound location to correct signaling information, such as the Caller ID in SIP headers, is within Session Manager itself. The DigitConversionAdapter is a specific tool designed for this purpose. It can modify the P-Asserted-Identity (PAI) and From headers, which Avaya Aura® Messaging (AAM) uses to identify the caller's mailbox. Using fromto=true ensures the From header is also manipulated, providing a comprehensive fix before the call reaches AAM.

A. The clid-numbering form in Communication Manager is primarily intended for manipulating Calling Line Identification on ISDN trunks, not for internal SIP entity routing via Session Manager.

B. Creating a caller ID modification rule in AAM is a workaround that corrects the number after it has been incorrectly received. The best practice is to fix the signaling issue at its source or within the core routing element (Session Manager).

D. The public-unknown-numbering form in Communication Manager is used to format the calling party number for calls going out to the public telephone network (PSTN), not for an internal SIP trunk to AAM.

1. Avaya Aura® Session Manager Documentation:

Administering Avaya Aura® Session Manager, Release 8.1.3 (NN43001-600, November 2021). In the chapter "Adapters," the section on "DigitConversionAdapter parameters" details how this adapter is used to modify digits in various SIP headers, including P-Asserted-Identity and From. It explicitly mentions the use of parameters like fromto to control which headers are modified for calling party information. (See Chapter: Adapters, Section: DigitConversionAdapter parameters).

2. Avaya Aura® Communication Manager Documentation:

Feature Description and Implementation for Avaya Aura® Communication Manager, Release 8.1.3 (03-603569, November 2021). The section "Calling Party Number - Public Network" describes the function of the public-unknown-numbering form for external calls. Another section, "Calling Line Identification (CLID) on ISDN-PRI Trunks," describes the clid-numbering form, confirming these are for specific, non-SIP trunking scenarios. (See Index for "public-unknown-numbering" and "clid-numbering").

3. Avaya Aura® Messaging Documentation:

Administering Avaya Aura® Messaging, Release 7.1 (NN43100-600, June 2017). In the chapter "Administering telephone user interfaces," the section "Caller ID modification rules" explains that these rules are used within AAM to "modify the format of the caller ID that the system receives." This confirms its role as a receiving-end application-level adjustment, not a core network signaling fix. (See Chapter: Administering telephone user interfaces).