IP telephony cluster over internet

[HNETENG]

If I have a local site with LAN Network that has CUCM Publisher, CUCM subscriber and some IP phones. This LAN network is connected to the internet through firewall and router. And there is a remote site over the internet which has another CUCM Subscriber.

Can I have a high available IP telephony scenario by registering the IP phones on the local CUCM subscriber on the same LAN and in case the local CUCM subscriber goes off, then the IP phones can join the remote CUCM subscriber over the internet which is part of the single CUCM cluster over built over internet.

Note: the RTT of the internet circuit is around 50ms and its speed is 50 mbps.

[b.winter]

If you meet the requirements for a Cluster of WAN, then technically there should be no problem.
But I personally wouldn't advise it, because the internet itself is not a reliable medium (no QoS).

[HNETENG]

Thanks, So what do you recommend for such scenario as another alternative? 

[b.winter]

MPLS, private connections, ... something with QoS

[HNETENG]

If we considered that the internet circuit is of high quality with SLA with low RTT of 50ms and speed of  50 mbps. Can I add to the above scenario the below video conferencing devices:

(Qty 1  CS-KITPRO-PTZ4K-K9)

(Qty 1 CS-KITPRO-K9)

(Qty 1  CS-BRD75P-K9)

(Qty 1  Cisco Board Pro 75)

(Qty 7 CS-DESKPRO-K9 ) 

[Shalid Kurunnan Chalil · Accepted solution]

Hi there,

You mentioned that there is already a CUCM subscriber at the remote site. Is it currently functioning properly?

As long as connectivity with the CUCM at the main branch is maintained, you should be able to achieve what you are currently looking for. However, deviating from WAN design recommendations could lead to various issues and may even result in voiding Cisco TAC support.

Depending on the site's capacity, options such as MPLS or other site-to-site connections like point-to-point or VPN should be considered. Alternatively, an MRA setup can be relied upon if there are not many endpoints at the remote site, ensuring that every phone connects with the main branch call managers via MRA. Setting up an Expressway at the HQ enables branch phones and video devices to register with the HQ CUCM via MRA.

I strongly advise against connecting the call manager directly over the Internet. If MPLS is not feasible, consider establishing a secure site-to-site VPN connection to safeguard the traffic.

Regards,

Disclaimer:

Responses are based on personal knowledge and experience. Consider them as guidance. Other members may offer different perspectives or better approaches. No responsibility is assumed for outcomes; discretion is advised.