4.14.3.1 Retrieving the Contact and Group List for Clients that can Connect to the Email Server

After migration has completed, SIP enabled end points that can connect to the email server first subscribes to the enhanced Presence Server to know if the contact list has been migrated with the "ms-ucs" supported header

SUBSCRIBE
Contact: < user5@contoso.com m;opaque=user:epid:hQ0SP_5rl16D4JvbBGGtAQAA;gruu>
User-Agent: UCCAPI/15.0.3419.3001 OC/15.0.3419.3003 (AppName)
Event: vnd-microsoft-roaming-contacts
Accept: application/vnd-microsoft-roaming-contacts+xml
Supported: ms-ucs
Supported: com.microsoft.autoextend
Supported: ms-benotify
Proxy-Require: ms-benotify
Supported: ms-piggyback-first-notify
Proxy-Authorization: TLS-DSK qop="auth", realm="SIP Communications Service", opaque="0A9339AD", targetname=" exbox.exchange.corp.microsoft.com", crand="e8b69f85", cnum="3", response="98ccabbd2f338e344bcf43657094492c4460b932"
Content-Length: 0

Response from the enhanced Presence Server terminating the subscription with a 2165 diagnostic code:

SIP/2.0 488 Not acceptable here
Authentication-Info: TLS-DSK qop="auth", opaque="4671A717", srand="FA78E074", snum="5", rspauth="0f99e36e9009f0fff70a32c0524bd59cc5ae5cd9", targetname="SERVER.contoso.com", realm="SIP Communications Service", version=4
From: "User 5"<sip:user5@contoso.com>;tag=6705176eed;epid=a8716485d4
To: <sip:user5@contoso.com>;tag=DD687A6743502E056B92FABCF6DC7140
Call-ID: 112629f5c5f346b09e647523d70ea03b
CSeq: 1 SUBSCRIBE
Via: SIP/2.0/TLS 192.168.0.244:51649;ms-received-port=51649;ms-received-cid=82100
ms-diagnostics: 2165;reason="Contact subscription is not allowed as the user's contact list has migrated to Exchange.";source="SERVER.contoso.com"
Server: RTC/5.0
Content-Length: 0