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Multitenant Customer design of IP Telephony Solution

Hello Experts,


We have a customer that has owns two companies A & B in the same building Tower ( 16 Floors); 6 Floors is designated to each companies and Four is shared so that both employees are working along with each other, Each company has its own separate network ,data center and Unified Communication infrastructure .From UC prospective each Company has its own UCM Cluster totally on a different network and an Intercluster-trunk will be provisoned for them to communicate between each other. Nevertheless, Both companies are sharing the same Core switches (which are two 6807 VSS) in between so they have the ability to have inter operation.

Now customer requirements is that in shared floors, There are some meeting rooms with conference phones that belong to both companies ,Whenever Company-A or Company-B need to conduct a meeting, they require the IP Phone to provision the proper profile and the proper privilege for that meeting,Noting that the IP Phone device should retrieve also the proper IP Address concerned with the cluster they are logging in.For instance, Company-A is conducting a meeting so IP Phone should obtain an IP Address from Cluster-A and provision Extension Mobility Profile-A of Company-A with the proper privileges assigned to that profile. Likewise,Company-B if need to conduct a meeting the same process of obtaining information from Cluster-B with the concerned privileges.


The mainly challenges that we are facing are:

*Each company has a separate active directory ,Some users such as VIP (CEO & CIO) are having the same username on each domain.So in case of integration with CUCM does it :

a-Support multiple domain or not.

In case Yes,

b-some VIP users have the same username but in a separate domain such as and so in case accessing the Extension mobility profile ,They will enter the username of company-A for instance but how the callmanager will retrieve the information of the network and the profile concerned with cluster-A?

Please be advised that the customer is looking for  a way that is dynamic without any manual intervention from the administration for example.Also note that ISE is also will be deployed to be shared for both the two Companies so may be you guys has any idea how to involve it in between for Authentication purposes.


So,What could be the proper solution or method to utilize to provide such design.

If you have any question or concerns please let me know



Amr Sherif


I think you would save

I think you would save yourself a lot of trouble if you put two phones in the conference room.  One for each cluster.  A phone cannot be provisioned to 2 clusters at the same time while getting IP addresses from 2 different networks.  Once the ITIL file gets put on a phone, it's not going to be as easy to move it between the 2 clusters on the fly.

There is such a thing as Extension mobility cross cluster, but I am not sure that this would work for your use case.

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Community Member

Alternatively if you have two

Alternatively if you have two network connections in the conference room you could have the vlan configuration set so the phone could register to either company.   The phone would then need to be configured in each company's CUCM environment.


Something like this:

Jack A -> FA0/1 -> vlan9 -> DHCP Pool 100 with option 150 set to Company A TFTP

Jack B -> FA0/2 -> vlan19 -> DHCP Pool 101 with option 150 set to Company B TFTP

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Well we proposed to have a

Well we proposed to have a two phase plat for each network however, they refused it totally and need it to be only one network connection per each room. I know it's little bit constrain . 

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