EMCC, Emergency and "Clever" users

[carlnewton]

Hi all,

I just wanted to get some opinions on EMCC.  The specific scenario I am thinking of is as follows:

Four clusters, all running EMCC between each other.

User from cluster A is logged in on Cluster B

Lets say Cluster A is USA and Cluster B is UK.  Lets say the user has an emergency.

CSS Order is:

Adjunct CSS from Home Cluster roaming device pool

Line CSS from home cluster UDP

EMCC CSS from home cluster UDP

In the above scenario, the user dials 9911 for emergency (Since he is american)

Adjunct CSS captures it, routes to standard local route group

call is pushed over to UK Cluster

UK clusters EMCC SIP Trunk uses inbound callling search space which has a translation for 9.911 to 9.999 and call routes successfully to UK emergency services.  Is this understanding correct? (That i need translations in the inbound CSS for EMCC SIP Trunk for emergency calls?)  If this is the case, do I need a translation for every countries emergency number that this server will peer with for EMCC?  E.g 9.999, 9.112, 9.000,

What about if the USA user is clever, and calls 9.999 because he is in the UK? His home cluster will not recognize this.  Should I add a pattern for 9.999 at the top of the users EMCC CSS on his device profile that routes to standard local route group? Pushing the call over to the UK?

If this is the case, is it the same for multiple countries?  should all emergency numbers for every cluster be configured at the top of the EMCC CSS that route to standard local route group?

If this is the case, how does CUCM know which cluster to route the call to? does it look at the visiting phones normal registration IP address and send it there?

Sorry for all of the questions, but there are a lot of intricacies to this that I Cant think of the answers to!

[Ayodeji Okanlawon · Accepted solution]

Carl,

In EMCC all attempt is made to maintain the local dialing habit of a user except only in emergency cases. Because of emergency requirements etc, roaming users have to dial the emergency number for the visiting cluster where they are currently resident, even though the phone that is used to make the call is registered to the home cluster.

This is where your adjunct CSS comes in. Its single purpose is for emergency.

For every visiting cluster you need to define the emergency on that cluster. Eg if

Cluster A is going to be visited by Cluster B (US), cluster C (APAC), you will need to configure the emergency number for cluster A on the adjuct CSS of cluster B and C.

So in this case here, the US user visting UK, must dial 9.999 not 9.911. Once that happens you can use the adjunct CSS to route it to the relevant gateway (LRG etc)

[carlnewton]

I think Ayodeji is correct in that EMCC is only designed to allow emergency calls in your current country of location and I am over complicating things to try and make it do every emergency number.

I think the solution is to just make it so the user can dial the local emergency number and leave it at that!

[Vivek Batra]

First point, you don't need to use Adjunct CSS in this case (if user dials 911 in UK) since USA user (when in UK) is dialing it's local emergency number (911 or 9.911) which will be dialed by USA users as well (when in USA). Adjunct CSS only makes sense if USA user (when in UK) dials the UK emergency number and this call has to be processed first by USA cluster. Since except EMCC user, no one in USA will ever dial UK emergency number, it makes sense to keep those numbers in separate partition and CSS and assign only to EMCC users with the help of relevant device pool.

UK clusters EMCC SIP Trunk uses inbound callling search space which has a translation for 9.911 to 9.999 and call routes successfully to UK emergency services.  Is this understanding correct? (That i need translations in the inbound CSS for EMCC SIP Trunk for emergency calls?)  If this is the case, do I need a translation for every countries emergency number that this server will peer with for EMCC?  E.g 9.999, 9.112, 9.000,

Your understanding seems correct. UK site (in the position of visiting cluster) should be capable to get emergency calls of all peered countries and translate it to relevant local emergency number.

What about if the USA user is clever, and calls 9.999 because he is in the UK? His home cluster will not recognize this.  Should I add a pattern for 9.999 at the top of the users EMCC CSS on his device profile that routes to standard local route group? Pushing the call over to the UK?

This is the case I was mentioning before with respect to usage of Adjunct CSS. Since USA user when in US will never dials 999 for emergency. But scenario changes when the same user goes to UK and then dials 999. Hence you need to configure 999 as route pattern in USA cluster and keep in separate partition which can be seen only by Adjunct CSS and assign Adjunct CSS to device pool being used by EMCC user. With the help of correct device pool assignment, you will ensure that respective partition (999) will be seen by EMCC user only when roaming to UK cluster.

If this is the case, is it the same for multiple countries?  should all emergency numbers for every cluster be configured at the top of the EMCC CSS that route to standard local route group?

In my opinion, NO. To clarify this, let us add one more country viz India where emergency number is 100. If USA user now roams to India and dial 100, this call will first processed by USA cluster. First of all, you should have correct device pool associated with Indian phones so that desired Adjunct CSS can be applied. So in my opinion, USA configuration should look like as follows;

Device Pool - UK

Device Pool - India

Route Pattern - 999/uk_emer_pt

Route Pattern: 100/india_emer_pt

Adjunct CSS: uk_emer_acss (include uk_emer_pt here)

                          india_emer_acss (include india_emer_pt)

Now assign uk_emer_acss to UK device pool and india_emer_acss to India device pool.

With the help of geolocations, ensure that when UK phones register to USA cluster, UK device pool is being used and same is when Indian phones register with USA cluster.

In this way, you will ensure that when USA user goes to UK, s/he will be allowed to make 999 only for emergency with the help of correct device pool and Adjunct CSS. S/he won't be able to dial 100. When same user goes to India, s/he will only be able to dial 100, not 999.

So point to be noted here, when user roams to visiting cluster and dials the emergency number which is local to visiting cluster (say 999 or 100), this should be controlled by Device Pool and Adjunct CSS. On the other side, if user dials the emergency number which is local to home cluster (say 911), this can easily be taken care using Line CSS or EMCC UDP CSS.

If this is the case, how does CUCM know which cluster to route the call to? does it look at the visiting phones normal registration IP address and send it there?

Since from call routing perspective, there are two entities viz Home Cluster and Visiting Cluster. It is your home cluster who decides where to route the call. In SLRG is not used, home cluster will route the call to appropriate gateway. If SLRG is used, it will forward the call to visiting cluster (where you're now). Now it's upto Visiting Cluster EMCC SIP Trunk configuration how to route this call.

Please check the following link if it helps;

https://supportforums.cisco.com/blog/12588666/extension-mobility-cross-cluster-emcc-few-logical-aspects

- Vivek

[carlnewton]

Hi Vivek,

Thanks. The way i understood it was that Adjunct CSS Was used for exactly that - When a USA user dials 911 when in the UK. You are correct in that the call would work in this case without adjunct CSS, however the call would go to the USA emergency services when the caller is in the UK which is undesired.

"This is the case I was mentioning before with respect to usage of Adjunct CSS. Since USA user when in US will never dials 999 for emergency. But scenario changes when the same user goes to UK and then dials 999. Hence you need to configure 999 as route pattern in USA cluster and keep in separate partition which can be seen only by Adjunct CSS and assign Adjunct CSS to device pool being used by EMCC user. With the help of correct device pool assignment, you will ensure that respective partition (999) will be seen by EMCC user only when roaming to UK cluster."

I read in the EMCC Guide:

Adjunct CSS (new)
May skip Adjunct CSS configuration if home cluster and visiting cluster share the same emergency pattern.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/8_0_2/ccmfeat/fsgd-802-cm/fsemcc.html#wp1461291

So i was reluctant to put 9.999 in adjunct CSS for US cluster when UK uses 9.999 for emergency as well. How does CUCM classify the "emergency pattern"? Is it by the contents of the Adjunct CSS? If so it may cause a problem as the adjunct CSS for all clusters will have at least two numbers that are the same (Since we have four clusters)

I have also replied to the post below if you want to have a read.

[Vivek Batra]

Hi Carl,

Thanks. The way i understood it was that Adjunct CSS Was used for exactly that - When a USA user dials 911 when in the UK. You are correct in that the call would work in this case without adjunct CSS, however the call would go to the USA emergency services when the caller is in the UK which is undesired.

You are right Carl however my presumption was for emergency calls, most preferred option is to use SLRG. Hence in this case, even if Adjunct CSS is not used and USA cluster receives call for 911 (when user is in UK), either Line CSS or EMCC CSS will see the 911 partition and because of SLRG is being used, this will get routed back to UK cluster where respective translation will be applied to convert it to 999.

So i was reluctant to put 9.999 in adjunct CSS for US cluster when UK uses 9.999 for emergency as well. How does CUCM classify the "emergency pattern"? Is it by the contents of the Adjunct CSS?

I hope you are using EMCC in congestion with geolocations and appropriate device pool. Each cluster should have dedicated device pool (called roaming device pool) for all other clusters. For example, if you have cluster in USA, UK, APAC and Africa, USA cluster should be configured with three different device pools dedicated for each cluster. 

Now for the users who have a habit of dialing local emergency numbers while in visiting cluster, home cluster will be able to identify relevant Adjunct CSS because of location specific device pool. In this case, USA cluster should have three Adjunct CSS to take care of calls from UK (999), APAC (100) and Africa (112) cluster.

If so it may cause a problem as the adjunct CSS for all clusters will have at least two numbers that are the same (Since we have four clusters)

Not compulsory that is what I think so. Can you please let us know what all regions where these 4 clusters are spread with their local emergency number? I will able be able to comment better then.

I have also replied to the post below if you want to have a read.

Yes, I saw, thanks. In that case, just need to give appropriate training to end user.

- Vivek