Hi Ted,
We are in the process of rolling out call manager 6 cluster in Europe. Currently We have call manager 5 Cluster in NA.
1) Inherited the system. ( It has 4 digit dial plan which will be starting to overlap soon)
2) We have inter cluster trunk setup ( no gate keeper)
3) VOIP will be deployed in France, UK, Romania, Germany Sweden and more….
a) since these countries use different dial plans ( Dial different length of digits , Emergency services etc…
b) Possible integration into a Avaya and CME deployment)
What is the best dial plan for this situation?
Currently the Consultant has recommended 5 digit dial plan?
1) What about site codes? for each country or office location?
How do get out of this mess…. I scoured the net and found no real world examples. I have ready the SRND but I am still lost. I have searched the Cisco net forms also.
Many Thanks in advance.
Raj
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Hi Raj,
CCM dial plans are really one of those things that takes a lot of thoughtful planning to get right. You not only have to look at what your current infrastructure is, but you also have to allow it to scale to future growth.
The 4 digit dial plan is pretty common from what I’ve seen used today. Typically you will see the 4 digit extension correlate to the last 4 numbers of the user’s PSTN DID number
For example,
512-555-1234 and the user having extension 1234
This takes some careful planning to make sure you get things right when ordering your DID ranges, but you can usually come pretty close to getting what you need without wasting too much. This is a pain too, because you can end up with last 4 of the DID overlap as well…
Figure you get about 8000 extensions out of 4 digit dialing (1000-8999). You usually don’t see anything that starts with 0 or 9. We usually prepend 9 to anything off-net (outbound PSTN call).
So you have to ask yourself if 4 digit dialing is going to provide enough extensions based on the number of users you have on the cluster (leaving room to grow). If you currently have 4 digit extensions on your NA cluster and not running into scalability issues, you can probably stay with that. On your EMEA cluster, you may find yourself having overlap with the NA cluster if you’re also using 4 digit dialing in your CCM 6 cluster.
If 4 digit dialing is enough extensions for each region, you don’t really have to change as long as there is some room to grow. What you can do is utilize a route-pattern in each cluster that looks something like this ::
8.xxxx
This would send everything prepended with 8 and 4 digits out the intercluster trunk to the other CCM cluster. This would allow you to use 4 digits that overlap in each region while using 8 as an on-net dialing code to reach the other region. You would also want to make sure that neither site is using extensions that begin with 8 which means that takes you down to 7000 extensions available (1000-7999).
Here’s what I would suggest. Keep in mind I’m making some assumptions here.
All too easy (2 sites/clusters and 7k extensions in each site) ::
Watch your discard digits so you don’t get a loop!
NA cluster
1000-7999 – Extensions for phones (7000 extensions)
9 –prepending to off-net calls (PSTN)
8.xxxx – reserved for on-net dialing (send to EMEA cluster)
EMEA cluster
1000-7999 – Extensions for phones (7000 extensions)
9 –prepending to off-net calls (PSTN)
8.xxxx – reserved for on-net dialing (send to NA cluster)
Room to grow (10 separate sites/clusters and 7k extensions in each site) ::
NA cluster (basically echo this same config on all the clusters)
1000-7999 – Extensions for phones (7000 extensions)
9 –prepending to off-net calls (PSTN)
82.xxxx – reserved for on-net dialing to cluster 2 (cluster 2 = EMEA)
83.xxxx – reserved for on-net dialing to cluster 3 (cluster 3 = Japan)
84.xxxx – reserved for on-net dialing to cluster 4 (cluster 4 = CME-Thailand)
85.xxxx – reserved for on-net dialing to cluster 5 (cluster 5 = Avaya PBX)
8[6-9].xxxx – reserved for future use (only a couple more clusters left to grow)
Over Kill? (2 digit site code and 7k extensions in each site) ::
NA cluster (basically echo this same config on all the clusters)
1000-7999 – Extensions for phones (7000 extensions)
9 –prepending to off-net calls (PSTN)
812.xxxx – reserved for on-net dialing to cluster 2 (cluster 2 = EMEA)
813.xxxx – reserved for on-net dialing to cluster 3 (cluster 3 = Japan)
814.xxxx – reserved for on-net dialing to cluster 4 (cluster 4 = Australia)
815.xxxx – reserved for on-net dialing to cluster 5 (cluster 5 = China)
816.xxxx – reserved for on-net dialing to cluster 6 (cluster 6 = CME-Thailand)
817.xxxx – reserved for on-net dialing to cluster 7 (cluster 7 = Avaya-Texas)
818.xxxx – reserved for on-net dialing to cluster 8 (cluster 8 = Avaya-New York)
8SS.xxxx – reserved for future use (where SS equals 2 digit site code plus 4 digit extension)
So as you can see, there really is no right way to do it. It all depends on your current needs as well as future. You have to take into consideration your users as well. The more complicated you get with the dial-plan, the more trouble tickets it may generate for you. You may have to create a cheat-sheet for your users so they can quickly lookup what to dial when calling a particular person. Active Directory might be a really great place to store directory information for your users. If I want to call someone in the US and I’m on the NA cluster, I should be able to dial their 4 digit extension, or 81.1234 (where 8 is on-net and 1 designates the US cluster). Appropriate translation patterns will be needed. When you are finding yourself entering lots of route patterns and translations in each cluster (they will get redundant), you really need to consider using a gatekeeper. For example you could send all calls on the NA cluster with 8[2-9]xxxx to the Gatekeeper which has the full dial plan. That way you are doing little configuration in CCM and having it centralized on your gatekeeper(s).
Also consider what your users are already used to doing. If you find that 7k extensions is not enough to cover each cluster, you may not have a choice but to go with 5 digit extensions (again, you have to assess this). How easy do you want to make it for them? Is an 8 digit on-net code plus 2 digit site code + extension going overboard? I guess it all depends on how big your global network is? How important is matching up the extensions with the last 4 digits of their DID numbers? Renumbering a whole cluster would not be fun, but you may have to do so if you have outgrown 4 digit extensions.
You may want to consider making the site code part of their actual extension that shows up on their phone (vs. just discarding it). That way when Ted in the US gets asked by Bob in the UK what my extension is, I can look at my phone and say 11000. If I ask Bob what his is, he may say 21000. The last 4 of my extension may or may not match up with my PSTN DID (my DID might be 512-555-1000), it just depends I guess. Hopefully we have been properly trained to dial an 8 before calling each other. Making the site code part of the actual DN and not something that gets discarded with a route-pattern may make calling each other easier. If you do this, you will have globally unique directory numbering. If you use a 2 digit site code, you may end up with having 6 digit extensions (i.e 111000, where 11 is in the US and 1000 is the user). This seems like a lot of digits, but it also adds organization because you would know that anyone with a DN that starts with 11 is in the US.
So find out what’s going to scale well while still making it somewhat intuitive for the users. Just remember, 7 digit dialing from the US to overseas is still a lot faster than dialing over the PSTN (plus you are saving $ by staying on-net!). Have a good wiki or dial plan website for your company so they know exactly how to use the phone system. End-users don’t like change, so find something that’s going to scale!
Also, if you are using Unity in different regions, you want to be careful about overlapping extensions as well.
Hope this helps,
Ted