Registered to the experimental Calendar Access Protocol, but in practice it is almost always a dynamically assigned Windows RPC endpoint.
IANA assigns 1026 to cap, the Calendar Access Protocol, an experimental protocol (RFC 4324, 2005) that carried iCalendar operations over BEEP; the RFC names 1026 as the default port a Calendar Store listens on. CAP was never widely implemented and you will effectively never meet one. What you do meet on 1026 is a Windows box: Windows 2000, XP and Server 2003 allocated dynamic RPC and DCOM endpoints out of a low range starting at 1025, so 1026 is one of the first ports handed to whatever RPC service starts early, and nmap fingerprints it as msrpc. Vista and Server 2008 moved that range to 49152-65535, so a modern host answering here is running something else entirely.
Do not expose
The realistic listener is a Windows DCE/RPC endpoint, which has no business on a public IP; and since the binding is dynamic you cannot know what service is behind it without asking the endpoint mapper on 135.
$ nmap -Pn -sV -p 1026 TARGETSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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Corrections or a missing port? Reply @rimrocksystems.