The Connection Mailbox Sync service uses four connections by default; above 2,000 users or 80 ms round-trip latency the design guide's formula is connections = (single-inbox users * (latency in ms + 15)) / 50,000, with a maximum of 64 and never fewer than four.
Checked 2026-09-30
The maximum number of connections is 64. Never reduce the number of connections to fewer than four.
- Vendor
- Cisco
- Product
- Cisco Unity Connection
- Subsystem
- unified messaging
- Deployment
- on-premises
- Region
- not restricted
- Release range
- Release 15; formula written for Exchange CAS and EWS
- Checked
- 2026-09-30
Sources
- Design Guide for Cisco Unity Connection 15 - Single Inbox — Cisco Systems · tier 2 current vendor documentation · Single Inbox > calculating the number of connections
Cite this note
APA
WarmTransfer. (2026, September 30). Setting up Unity Connection single inbox with Microsoft 365: source note unity-connection-single-inbox-setup-sync-connections. WarmTransfer. https://warmtransfer.net/knowledge/claims/unity-connection-single-inbox-setup-sync-connections
BibTeX
@misc{warmtransfer-claim-unity-connection-single-inbox-setup-sync-connections,
title = {Setting up Unity Connection single inbox with Microsoft 365: source note unity-connection-single-inbox-setup-sync-connections},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/unity-connection-single-inbox-setup-sync-connections},
note = {Source note unity-connection-single-inbox-setup-sync-connections, checked 2026-09-30}
}