Cloud Telephony – Technical comparison between Webex Calling and UCM Cloud

How do you determine which cloud is right for your enterprise telephony needs ? What are some key determining factors which can be helpful to choose the right cloud and the architecture? This blog offers key technical perspectives in strategizing your journey to cloud telephony across features, functionality, scalability, security, compliance and API Integrations for Webex calling and UCM cloud.

Few months back I wrote a blog on cloud calling decision flow example which might be helpful perspective before jumping to this blog. Note that I have deliberately omitted HCS cloud in this blog.

So lets take a look few technical perspectives for both Webex calling and UCM cloud:

Target Customer Segment

UCM cloud is targeted mainly towards enterprise customers (10,000+ users) while Webex calling cloud is targeted towards SMB and mid-market customers (10-1000 users). But its Important to note that this is not a platform limitation in supporting greater number of users, for instance Webex calling can support far greater than 1000 users on a use case basis.

Cloud architecture

UCM cloud architecture involves protocols, components and design similar to its on-perm data center counterpart and supports all deployment models except for clustering over the WAN. Every customer within the UCM cloud has a dedicated private cloud resources that includes call control, IMP, unity, emergency responder and Expressway services. Webex calling cloud on the other hand is a multi-tenant architecture where a common application code (call-control) is shared by multiple customers while maintaining strict application boundaries between different customers. Additionally Webex Calling cloud has SBC on the access side for customer traffic termination and peering SBC to connect with multiple PSTN providers. The below layout shows the application architecture of both these clouds.

Webex Calling and UCM Cloud – Overview of application architecture, connectivity, API’s and Integration layer

Peering options to the Cloud

Please refer to the connectivity layer from the above layout

UCM Cloud: To connect your branch, HQ or campus to the UCM cloud you can either use a partner or customer connected model. In the customer connected model also called ‘direct connect’ there are multiple options to connect customer network with the UCM cloud. These are Webex Edge, VPN, SDWAN, Fiber or MPLS. Lets say want to leverage Webex edge connection since you already have a Equinix service for other application traffic like O365. Here is how your connection from HQ to the UCM cloud could look like.

HQ –>WAN–> Data center –> Equinix ECX Fabric –> Webex backbone –> UCM Cloud

Webex Calling Cloud: Connecting your HQ, branch or campus to Webex calling cloud is over the public Internet. The SIP/RTP traffic will transit your enterprise firewall and public Internet to leverage resources from the Webex calling cloud. If you leverage a partner for hosting PSTN gateway, the SBC from the Webex calling cloud communicates with partner multi-tenant gateway over the Internet as well.

PSTN Connectivity

Both UCM cloud and Webex Calling cloud do not include PSTN services. The options are customer or partner hosted local gateways, additionally Webex Calling hosts SBC within its cloud to peer with regional PSTN providers. The PSTN call flow for both the clouds are detailed in the connectivity layer from the above layout.

I recently wrote a blog dedicated to PSTN options with Webex cloud calling which offers in-depth details on the PSTN connectivity.

API support

UC Manager supports robust API’s for configuration and provisioning (e.g.,AXL) and device monitoring and call control (JTAPI). These same robust set of API’s are available from UCM cloud as well. Webex calling cloud API capabilities are still in infancy and supports subset of features as compared to UCM.

Feature Parity

Although Webex calling and UCM cloud are enterprise grade platforms, without any doubt UCM cloud offers broadest set of features for calling and voice messaging in its current state. For detailed list of UCM cloud features please refer to this data sheet. Webex calling cloud also offers robust set of telephony features for enterprises which can be found here. It also important to note that Cisco is accelerating the development of new enterprise features on the Webex calling platform which can be found in whats new in Webex calling

Global Availability

Both Webex calling and UCM cloud services are available across NA, APAC and EMEA. Its Important to note that for point-to-point voice and video calls, the media is anchored in Access SBC in case of Webex calling which means that the traffic needs to be terminated in the Webex calling cloud for all calls and goes through the internet. This can lead to sub-optimal user experience especially for multi-region deployments. This is addressed by leveraging regional SBC for media but the SIP signaling still can traverse inter-region even for local point to point calls. Please refer to this preferred architecture for Webex calling to understand these media flows in detail. Whereas in case of UCM cloud media flows directly between two end points in case of point-to-point calls which doesn’t exit the enterprise boundary.

Telephony Integration with Messaging Apps

If you are currently using Webex Teams, Microsoft teams or Slack as your enterprise messaging app, both UCM and Webex cloud calling can be integrated into these messaging apps delivering rich telephony features. More details on this announcement.

Security and Compliance

Cisco’s leadership in Cloud security means that one can be assured that customer’s receive best-in-class security whether its at the application or data center layer and tools and processes to ensure secure design, development and testing of the applications. Webex calling cloud security white paper can be found here. Whereas UCM cloud apps are hosted within Webex data centers and all of the Webex security best practices are applied for UCM as well.


Preferred architecture for Webex calling

Webex calling security white paper –

Cisco Live session from Seongho Hong on Webex Calling

Cisco Live session from Stefano Giorcelli on UCM Cloud

Cisco Live session from Paul Giralt on UCM platform API’s

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: