3CX 
SIP Communicator
LinPhone
iSIP
Ekiga
Broad Support for Open Clients
openUC is an open and standards based solution and as such it supports a broad variety of clients for voice, video and instant messaging. As an open solution openUC supports many clients. This is a key advantage to the user as it reduces cost, accelerates innovation, and allows users to use their favorite client.
eZuce Communicator
eZuce Communicator is a powerful and user friendly Instant Messaging & Presence client for the openUC system, based on the XMPP (Jabber) standard. It is localized to a lot of regions and languages and supports all the usual IM features including profiles, avatars, group chat, file transfer and chat history.
Supported platforms:
eZuce Communicator is a fully featured multi-platform IM client:
- Chat
- Group chat
- Federation
- Chat history
- File transfer
- Profile management and lookups
- Avatars
- Flexible authentication mechanisms including LDAP / AD
- Easy mass deployment
- Localized
- Derived from the widely used open source Spark client
Nested Portlets
Counterpath Bria
The Counterpath Bria softphone supports voice, video, instant messaging and presence in one powerful client. openUC facilitates mass deployment and automated provisioning of the Bria client. Bria is the right client if your primary applications are voice and video, but you don't want to miss out on the integrated IM & Presence capabilities.
Supported platforms:
Bria comes with a host of features:
- High Definition Audio provides exceptional clarity and voice quality
- High Definition video - View, send and receive video in high-resolution HD (960x720p) video
- New GUIs for Windows and Mac - Select a light or dark colored interface; smooth transition effects and animations; Mac version reflects standard Mac design
- Improved usability - Simpler design and improved task flow for transfers, conferencing and multi-call handling; improved preferences and layout
- Improved accessibility - Scale Bria to different sizes
- Improved login options - Select from a number of login options; DHCP discovery (provisioning server)
- HID USB support - Support for plug-and- play HID-compliant devices with the option to personalize buttons to control Bria (Windows only)
- Troubleshooting assistant - Easy to use self testing to identify common softphone/VoIP issues; Provides call quality statistics
- Alert List (Buddy Pounce) - Select a contact or group of contacts and be notified when their phone and presence status changes
- Address Book Support - Synchronize your contacts with Microsoft Outlook® personal address book (Windows only); Supports Mac Address Book (Mac only)
- CLI and CRM integration support - New API to allow integration of Bria call flows with other applications such as Customer Relationship Management systems; CLI (Command Line Interface) compliant with RFC 4967
- Call Pick Up and Join - Bridged Line Appearance (BLA) support for workgroups allows members to pick up or join other calls
Bria for iPhone
Bria iPhone Edition is a SIP-based phone for Apple iPhone and iPod touch that uses a Wi-Fi or 3G connection to make and receive calls.
Using the iPhone or iPod's existing contact list, Bria iPhone Edition facilitates easy and effective communication management with an intuitive interface that accommodates multiple calls. Call functionality includes the ability to swap between two calls, merge and split calls and perform attended and unattended transfers.
Bria iPhone Edition incorporates advanced security settings which allow for secure call signalling and audio encryption. It also contains enhanced audio features including G.711, GSM, and an optional G.729 codec.
iSoftPhone for Mac
SIPDroid for Android
Adds native SIP/VoIP to Android's dialer/contacts. Make and receive calls over Wifi, 3G, and EDGE with perfect voice quality and lowest delay. SIPDroid supports a wide range of audio and video codes for both low bitrate as well as HD audio calls. SIPDroid is the most widely used SIP client on the Android platform.