Below are some best practices for call processing in a Unified CM:

• CM Groups – CM groups must include Unified CM nodes from both data centers within a region.

• Create different CM groups for different entities (phones, trunks, etc.).

• Additional services should not be enabled, for example, starting the CallManager service on the Publisher, as they may directly impact the scalability of the platform.

In the context of Unified Communications (UC) and VoIP (Voice over IP), a codec is responsible for encoding audio or video streams into a compressed format for transmission over a network and decoding the streams at the receiving end for playback.

Below is a codec recommendation for integration with Webex Calling Multi-tenant or Webex Meetings:

• Where customer do not want to use OPUS and/or G722 but still wish to connect to multi-tenant for Webex Contact Center or Webex Meetings for Webex Edge Audio they need to create appropriate Codec Preference Lists that prioritize G711 over the other codecs.

In a Dedicated Instance environment, media resources are software or hardware-based services that provide essential functionalities for voice, video, and collaboration features. These resources facilitate tasks like conferencing, music on hold (MoH), media termination, and media transcoding, enabling seamless communication and collaboration across the network.

Below are some best practices:

• MTP Required check box – Not recommended for a Dedicated Instance deployment. If the MTP is required for all the calls due to a 3rd party integration, please use hardware/software MTPs configured on a router on-premises.

  Cisco IOS MTPs are recommended over Unified CM MTPs because, Cisco IOS MTPs provide additional scalability and greater functionality, such as support for additional codec types, multiple media streams, and the pass-through codec.

• MRGs must include media resources from Unified CM nodes from both data centers within a region.

• Cisco recommends that you configure and deploy multiple MoH servers for completely redundant MoH operation. If the first MoH server fails or becomes unavailable because it no longer has the resources required to service requests, the second server can provide continued MoH functionality. For proper redundant configuration, assign resources from at least two MoH servers to each MRG in the cluster.

SIP trunks play a critical role in modern voice over IP (VoIP) systems by using the SIP protocol to establish, manage, and terminate communication sessions. SIP trunks are typically used to connect the Dedicated Instance environment with External telephony service providers (e.g., PSTN), other Unified CM clusters or VoIP systems for internal communications or Third-party SIP-enabled applications like contact centers or voicemail systems.

Route List is a configuration element used to manage and control call routing. Route lists are commonly used in Unified CM to provide flexibility, redundancy, and load balancing for call routing.

Below are some best practices:

• Enable Run on all active Unified CM nodes on all the SIP trunks.

  Enabling Run on all Active Unified CM Nodes on SIP trunks is highly recommended because this feature allows outbound calls to originate from, and be received on, any call processing node within the cluster. Run on all Active Unified CM Nodes can also eliminate calls from being set up between call processing nodes within the same cluster before being established over the outbound SIP trunk.

• Enable Run on all active Unified CM nodes on all the route-lists.

• Enable SIP OPTIONS ping keep-alives.

  The SIP OPTIONS ping feature can be enabled on the SIP Profile associated with a SIP trunk to dynamically track the state of the trunk's destination(s). Cisco recommends using SIP OPTIONS Ping to dynamically track the state of each destination IP address on each SIP trunk and the collective state of the trunk as a whole.

• TCP is recommended within Cisco Collaboration Systems networks because it is a reliable and connection-orientated protocol with the capability to fragment and re-assemble large SIP messages.

• Best Effort (No MTP Inserted) eliminate the use of MTPs to create an Early Offer for voice, video, and encrypted calls over SIP trunks.

• Up to 16 SIP Trunk Destination IP Addresses

  SIP trunks can be configured with up to 16 destination IP addresses, 16 fully qualified domain names, or a single DNS SRV entry. Support for additional destination IP addresses reduces the need to create multiple trunks associated with route lists and route groups for call distribution between two Unified Communications systems, thus simplifying Unified CM trunk design. When IP addresses are used as destinations on a SIP trunk, < infromation required>

In a Dedicated Instance deployment, gateways are devices that connect the IP telephony network to external networks such as the Public Switched Telephone Network (PSTN) or other VoIP systems. They serve as interconnection points that allow voice and sometimes video traffic to pass between the Cisco VoIP environment and non-IP-based telephony systems. Gateways are typically deployed in customer or partner premises to provide PSTN services.

Cisco recommends using SIP gateways for their Dedicated Instance deployments. Below are some of the best practices for the SIP gateways:

• Create SIP Dial-peers to all the Call processing Unified Communications Manager (Unified CM) nodes.

• Enable Options Ping on all the dial-peers and select the correct transport option (UCP, TCP or TLS).

Emergency services in the context of Unified Communications (UC), such as in a Cisco Unified Communications Manager (Unified CM) environment, refers to the ability to support and route emergency calls (e.g., 911 in the United States, 112 in Europe) to the appropriate Public Safety Answering Point (PSAP). This ensures that callers can reach emergency responders, such as police, fire, or medical services, during a critical situation.

For US Customers only

• Cisco strongly recommends that you configure the system to recognize both the strings 911 and 9911.

• Cisco strongly recommends that you explicitly mark the emergency route patterns with Urgent Priority so that Unified CM does not wait for the inter-digit timeout (Timer T.302) before routing the call.

• In a multisite deployment, the dial plan configuration should ensure that the emergency calls are always routed through the PSTN gateway local to the site, thereby making sure that the emergency call is routed to the nearest PSAP within the jurisdiction. One of the mechanisms to achieve this could be to use the Local Route Group feature of Cisco Unified CM.

• For deployments with centralized PSTN access, the Unified CM administrator must verify that the PSTN provider will route emergency calls to the proper PSAP based on ANI or ELIN.

IP Phone Services in a Dedicated Instance environment refer to features and applications that enhance the functionality of Cisco IP phones. These services provide users with access to various tools and applications, such as extension mobility, corporate directories, call logs, and custom business applications, directly from their Cisco IP phones.

Below is a recommendation to allow resiliency for these services:

• Configure either a load-balancer or use DNS SRV to provide the necessary resiliency for IP phone services.

Voicemail in Dedicated Instance is a key feature that enables users to record, store, retrieve, and manage voice messages when they are unable to answer a call. Cisco provides voicemail solutions as part Dedicated Instance through Cisco Unity Connection (CUC), which integrates seamlessly with Cisco Unified Communications Manager (Unified CM) and other Cisco collaboration tools.

Below is recommendation to secure the signaling for voicemail:

• If the customer would like to secure the trunk to voicemail, they need to enable security on the existing trunk (provisioned as part of base configuration) and not create a new trunk. This allows the monitoring of the trunk as we monitor them by name.

Do not enable additional services on the provided infrastructure as it will impact cloud scaling calculation and may invalidate your SLA.

E.g., Do not run Unified CM service on the publisher, do not run extension mobility on all Unified CM nodes, do not enable TFTP or media services on additional Unified CM nodes, etc.