We have a requirement in Dynamics 365 Contact Center to route incoming calls to the agent who has been available for the longest duration within the current session (based on login or availability start time).

Currently, the available assignment methods such as Least Active and Advanced Round Robin do not meet this requirement:

• Least Active considers the agent’s last capacity release time across sessions (including previous days)
• Round Robin distributes work sequentially based on assignment order
• Neither method considers true availability duration from login or start of shift

✅ Business Requirement

When multiple agents are in “Available” status:

• The system should route calls to the agent who has been continuously available the longest within the current session
• Prioritisation should be based on:
• First logged-in agent
• Availability start time within the shift
• Ignoring activity from previous sessions

✅ Current Limitation

• No out-of-the-box option to sort agents based on availability duration or login time
• No system field exposed for “Available Since” or session-based availability timestamp
• Custom fields cannot be used in Assignment Rules (Order By)

✅ Business Impact

• Current routing may assign calls to agents who logged in later instead of those available since shift start
• Leads to gaps in expected fairness during shift-based operations
• Particularly impactful in service desk environments where agent shifts and availability play a key role in workload distribution

✅ Requested Enhancement

Introduce a routing option to:

• Assign work items based on Longest Available Agent (Session-Based)
• Consider availability duration within the current session only
• Optionally allow configuration to:
• Include/exclude previous sessions
• Define time window for activity consideration

This capability would help align unified routing with real-world shift-based operations and improve fairness in call distribution.