Background
Historically, users in ConnecttoTeams are able to be configured with an e164 Phone Number or an Extension Number, with no formal distinction between the two. One undesirable result of this approach is that extension numbers are displayed with a “+” and country code in the Teams dialer. E.g. a US-based user configured with extension 1000 will be displayed as +11000 in the Teams dialer, and an Australian user configured with extension 1000 will be displayed as +611000 in the Teams dialer.
Transitioning to Pilot Numbers
Starting with the release of the version 2.18 and the ACS Call App, ConnecttoTeams has begun transitioning to explicit support for extensions. In this new implementation, an extension must always be paired with an e164 Pilot Number. Put another way, ACS Call App users must be configured with an e164 phone number, or an extension plus a Pilot Number. This requirement will be extended to users of other services in the future.
Call Routing
For service that require explicit definition of extensions, ConnecttoTeams will route inbound calls as follows:
Extension Only: We will still accept calls with [ext]@[domain] format. For example, if the inbound call R-URI has the format of [ext]@[domain] but the user is configured with a Pilot Number and Extension, then calls will be routed correctly and the SIP INVITE sent to Teams will include the Pilot Number like INVITE sip:+12025550123;ext=12345@sbc1.contoso.com
Extension + DID: With this change we will now accept inbound calls with format of [phone number];[ext]@[domain] (eg. INVITE sip:+12025550123;ext=12345@sbc1.contoso.com). In this case, we will route the call to Teams correctly even if the user does not have a Pilot Number configured. If inbound call R-URI has the format of [phone number];[ext]@[domain] but the user is configured without a Pilot Number, then the SIP INVITE sent to Teams will not include the Pilot Number like (eg. INVITE sip:12345@sbc1.contoso.com).