Rule of thumb for provisioning ISDN-PRI

[navy1]

I have to order 15 ISDN-PRI toll free circuits. All will be part of a trunk group with one toll free number. Want to assign primary D channels but also have secondary D channels provisioned.

Does anyone know the rule of thumb as to how many primary D channels and how many secondary D channesl would be necessary for 15 PRIs in one trunk group? And how to have the B & D channels circuits provisioned? My example below only shows 1 primary, 1 secondary but maybe more are needed? Any info is appreciated.

circuits:
#1 - ch 1-23 B chnls, ch 24 primary D
#2 - ch 1-23 B chnls, ch 24 secondary D
#3 - ch 1-24 B chnls
#4 thru #15 - ch 1-24 B chnls

 

[hawks]

I have an option Sucsession 4.5 running 8 PRI's with 1 primary and 1 back up D. So far no issues, I think the Option 11C can go up to 16 before you need to add another group.

 

[EddieDuece]

I have 3 call centers each having 12 PRI's, and a couple of toll free #'s. Each center's PRI's are divided into 2 trunk groups with overflow (6 PRI's per group). I have 1 primary DCH, and 1 backup DCH. This has been running clean for over a year at each site. Your channels look configured correctly as well.

 

[johnpoole]

nothing wronge with your config, i run 18 pri;s with a single d and a backup.. if i would have placed the order i would have broke it down to two groups.. i perfer the split my trunks into two routes.. if i need to make a change on a route, i could take a route out of service during slow traffic make changes, get it back up without affecting service.. in 24 hour call centers, planning for maint is crutial

john poole
bellsouth business
columbia,sc

 

[EddieDuece]

Your right on the money John. When we installed the PRI's, they were misconfigured causing calls to drop sporatically. Once we figured out the cause, we shifted traffic from the primary trunk group to the secondary, and corrected the primary group's configuration. Once that was done, we did the same for the secondary, at all 3 call centers which worked great. A seemless fix. No after hours work is my preference!

 

[navy1]

Thanks hawks, EddieDuece, johnpoole for the info. I actually will have my trunks split in 2 trunk groups. Avaya has now recommended no more than 10 PRIs per trunk group and this thing is going to grow over time to almost 1000 channels. I'll need at least 4 TGs with overflow.

Have another question. Want to use "AT&T Trunk Sub-Group Overflow". Will have this big PRI trunk group but should all trunks get busy, want to overflow to other existing TGs, different TFNs. Looked on web for info as to how to provision - not finding much. Does anyone know where I could get some provisioning info? Thanks.