We have all heard the saying, “There’s never time to do it right but there is always time to do it over.” This is as true for Unified Communication deployment as it is anything else. Today I was talking to a gentleman that had recently started a new job managing a Cisco Unified Communications system. He mentioned to me that one of his largest headaches is how the calling search spaces and partitions are organized. OK, maybe the word organized is being a bit generous. This made me start to think… how many times have I heard this?
Calling search spaces and partitions are arguably one of the most important concepts to master in a Cisco Unified Communications environment. While they can seem complicated at first, they are fairly simple when you get down to the core of what they are and how they work.
As you may know, calling search spaces and partitions are used to create class of services within CUCM. For those that aren’t familiar these concepts think of it this way: a partition is assigned to a number. In order for a device to reach that number, they must have the number’s partition listed in their calling search spaces. A simple analogy is that of locks and keys. The partition is the lock; the calling search space is the key chain. If you have the key to the lock, you can reach the destination. I am not going to go any further into the explanation at this point as this is not the focus of this post. The focus is that of proper planning and organization of calling search spaces and partitions.
Let’s start with planning. Since calling search spaces and partitions determine which numbers various devices can reach, you first need to determine what types of numbers your dial plan will consist of. A typical dial pan consists of at least five types of destination numbers. These are:
- Local Numbers
- Long Distance Numbers
- Toll Free Numbers
- Intra-Company Numbers
- Emergency Numbers
Your environment most likely will include other destinations so the first thing you need to do is take a long hard look at all of the types of numbers your dial plan will consist of.
Next you need to think about the type of users you have within your company and the type of calls they will need to make as part of their everyday job. It often helps to look at the different job roles within your company and group those roles together based on the type of calls each needs to make. Often many different roles will need to make the same types of calls. By grouping the roles together you can reduce the number of calling search spaces you need. For example, if you have sales, warranty and billing departments and they all make the same type of calls you can create one calling search spaces for all of them instead of one for each department.
Now, of course, you are documenting all of this while you are planning. I know the dreaded D word… I don’t know why but it seems like very few techies like to document anything. Trust me, when you get to the point of actually configuring this stuff, it will go much smoother if you have it down on paper.
Once you have a clear picture of the types of destination numbers your dial plan will require and the types of callers you have, you can start creating the partitions and calling search spaces. Create a partition for each type of destination and a calling search spaces for each type of caller. Remember to keep it as simple as you can while ensuring you have deployed the most effective and secure class of service possible.