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We are seeing a surge of companies looking at migrating their unified communications infrastructure to full cloud or hybrid cloud and shift from capex to opex mode. They don’t want to handle complexity anymore and want a cloud provider to deliver those core communication services while they reap the benefits of subscription cost model and accelerated features deployment.

While the core collaboration services (calling, meetings and messaging) and integrations are delivered from the Webex cloud, the PSTN access method are left open with multiple options for the customers to choose from. This is done to ensure that customers meet their regulatory and unique call routing requirements while they transition to cloud communications. So whether you are running a global centralized or distributed call control with local gateways and want to strategize on cloud migration, the below options may come handy

Option 1: Let Cisco handle it : This option allows you to leverage Webex calling cloud and their global PSTN service providers for PSTN connectivity. You can further mix and match PSTN service providers depending on the location or the region. The Webex control hub allows you to establish the connectivity to your preferred PSTN provider on a site-by-site basis.

Option 2: Let a Cisco partner handle it: In this option you can select a cisco partner to be your local gateway PSTN provider. Your partner’s cloud essentially hosts a multi-tenant CUBE router and uses dial-peer configuration for separating voice and video traffic between different customers. Note that there is no connection needed between your UC network and the partners network since the peering happens directly between Cisco Webex control hub and the partners CUBE located in their data centers.

Note: If you plan to retain your existing call control (CUCM) along with Webex calling, then option 3 is preferable which is discussed next.

Option 3: I will handle it myself: This option allows you utilize your existing local gateway for PSTN connectivity. Cisco Webex cloud directly peers with your local gateway to route PSTN calls. One important item you want to consider is when you want to keep your existing call control (CUCM) with some devices attached to it. In this scenario you will peer Cisco Webex with your CUCM so that all the off-net calls coming from Webex are routed to the local gateway and on-net calls are routed to your CUCM registered devices.

Finally you can mix and match these options. For Instance for one location you can choose Cisco Webex calling as local gateway provider and for another location you can choose your local gateway as a way to connect to PSTN.

References:

Preferred Architecture for Webex calling: https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/Collaboration/hybrid/AltDesigns/PA-WbxCall.pdf

Collaboration transitions: https://www.cisco.com/c/en/us/td/docs/solutions/PA/mcp/MCPdocs.html#Calling