Re: CUCM and Voice Gateway and Route Plan

snahosany · ‎03-28-2011

Dear All,

I am to deploy CUCMBE 8 in a centralized model to serve some 300 users. But currently I am deploying in on central site, fully test and then moving forward to the other sites. I have just embarked on VoIP and CUCM and would like to have some clarifications from questions below:

1. Actually some sites would be using our own ISDN connection to make calls over the PSTN, i.e. users of some sites when calling PSTN would go through the WAN through our central site Voice gateway and then connec to PSTN. Do these sites need a voice router(gateway)? They do need at the moment SRST, because they have a backup WAN Link to the central site.

2. Currently to connect on WAN i have SHDSL and Wireless Point to Point Links, i.e. two routers that connects to the WAN. Is it needed that all Voice traffic to the WAN goes through the Voice Gateway?

3. Do you need compression over the WAN Link, currently i do believe that we use G711 by default, if i want to change to G729, how do i do it? Do i need Voice Router to have that done? or can be done through CUCM.

4. Route Plan. Currently at the Head office we would be using 2XXX extensions, and others would be using 3XXX, 9XXX etc.... My question is currently how can i make it possible that from Site A (Head Office) to reach Site B (3XXX) users must dial a site code for e.g. 300 for site B then followed by 3XXX, while users on site B communicate among themselves using 3XXX.

Any help would be much appreciated.

Thanks in advance.

frlindse · ‎03-28-2011

1. Actually some sites would be using our own ISDN connection to make calls over the PSTN, i.e. users of some sites when calling PSTN would go through the WAN through our central site Voice gateway and then connec to PSTN. Do these sites need a voice router(gateway)? They do need at the moment SRST, because they have a backup WAN Link to the central site.

Ans. If they have local circuits/connections to the pstn they would need a voice gateway. If they don't a voice gateway for SRST would only let them call one .another, SCCP based phones do not need a voice gateway between them and CUCM.

2. Currently to connect on WAN i have SHDSL and Wireless Point to Point Links, i.e. two routers that connects to the WAN. Is it needed that all Voice traffic to the WAN goes through the Voice Gateway?

Ans. Depends on what you are connecting to at the other end. If an inbound call is to an SCCP based phone there does not need to be a voice gateway for the WAN CUCM controls the phones directly without gateway assistance.

3. Do you need compression over the WAN Link, currently i do believe that we use G711 by default, if i want to change to G729, how do i do it? Do i need Voice Router to have that done? or can be done through CUCM.

Ans. To use G729 you would need to set up a Region in CUCM for the remote sites with G729 specified as the codec for use between that region and the central region.

4. Route Plan. Currently at the Head office we would be using 2XXX extensions, and others would be using 3XXX, 9XXX etc.... My question is currently how can i make it possible that from Site A (Head Office) to reach Site B (3XXX) users must dial a site code for e.g. 300 for site B then followed by 3XXX, while users on site B communicate among themselves using 3XXX.

Ans. Not sure why you would want to use a site codes if there is no overlap between the extension numbers? CUCM can route calls from any extension to any extension as long as the device with that extension is registered to it.

snahosany · ‎03-30-2011

Dear frlindse

Thanks for your response.

Relating to point 1

What i understood if they would be using our central site voice gateway for PSTN access, then on the remote sites their wont be any need for a voice router if they are not using SRST? Am i right?

Relating to point 2. The SHDSL links will connect both company's LANs, so from your response i dont see any need for a voice gateway. Please let me know if i am right on this point.

Relating to point 3

Currently some companies have DIDs for all users. So for example the last four digits on 2 sites is 9XXX, so they have asked to maitain their current local extensions to 9XXX. that is why probably i would use site codes because it was a requirement from them. Now this leads to another problem, on their current PABX, all sites uses 9 for off-site, to connect to PSTN.How can I at the same time maintain the 9XXX extensions and use 9 for offsite access.

Thanks a lot, I appreciate greatly your help and awaiting your reply on the above.