Call Center - Planning and Server Requirements

I am planning a 30 seat call center (E1 line). Two major requirements:

1 - High-Availability / DRBD / Active-Passive scenario
2 - Recording all incoming calls from customers.

I am looking at the Dell PowerEdge R510 servers. Could you please advise more with regards to the server hardware. I might be missing some considerations especially for storage as extensive recording will be taking place.

  • hot swap vs cabled hard drives
  • strategy for storing/rotating recordings
  • I will use the TE121B digital card
  • dual-port NIC on each server

Thanks in advance

with 8 PRIs i have to use two anyway

Yea, the switch is not something that fails, 99% of the time… anyway you still going with one FB that also becomes the single point of failure. Also will help if you want to have 2 FBs as well…

this is not best practice since the switch now become the single point of failure. for a two server cluster, redfone recommends direct connects and i support that. for bigger clusters [i have a 16 server cluster] switches are necessary but then you have to organize redundant switches to avoid the dread single point of failure.

Thanks sanjayws for your input.

What do you exactly mean by: “I would suggest to use a switch for TDMoE to auto failover”

Do you mean to connect the fonebridge to the Network switch instead of directly connecting it to the servers?

Fonebridge are really stable, we’ve done call centers of around 100 agents with 8 PRI exactly like how you would need installation in 3 days and running on the 4th…

I would suggest to use a switch for TDMoE to auto failover.

The installations are quite straight forward if you ask me.

DRBD with heartbeat will be perfecto in this case and if you use FreePBX, pay special attention to the databases etc…

the single E1 line and many other things have to do with the type of clients that hardly want to discuss things. they just want a quotation to check and compare prices. in other words to have a taste of it. I am pretty sure many requirements will change if they officially consider it.

I like this product so far. I still need to test it though and I hope to do that soon. I like the no PCI requirement …

I am planning to get a server with the following specs for the 30 seat call center. It looks an overkill but in case they want to expand … :

Dell PowerEdge R510
PE R510 Chassis for Up to Four 3.5" Cabled Hard Drives, LED

Intel® Xeon® E5620 2.4Ghz, 12M Cache,Turbo, HT, 1066MHz Max Mem

8GB Memory (4x2GB), 1333MHz Single Ranked UDIMMs for 1 Procs, Optimized

Hard Drives
1TB 7.2K RPM SATA 3.5" Cabled Hard Drive

Hard Drive Configuration
No RAID, Embedded SATA Controller for x4 Chassis

Internal Controller
No Controller

External Controller

Network Adapter
Intel Gigabit ET Quad Port NIC, PCIe-4

What do you think?

as you say, enough horse power to run a lot larger center… not quite sure what you are going to do with 8GB RAM

just out of interest, you indicated a 30 seat call center but you only have a single E1 line. that means if all 30 agents are talking, the call center has no capacity to queue calls. maybe that is deliberate but that is pretty unusual in my experience. most inbound call centers like to have queue capacity for efficiency reasons so usually you want more trunk lines than you have occupied seats.

for just two servers, best practice [now also advocated by red-fone] is in fact to direct connect to the servers using crossover cables but obviously that only applies to the devices that have two ethernet ports. personally i would prefer to pay a little more and get a model with 2 NIC ports.

i have over the last 5 years deployed dozens of these [i am working on two separate installs this week]. they have been flawless in all respects . they are extremely simple to install and really the instructions are going to be pretty much the same for all models.

[btw i have no relationship with red-fone other than being a customer]

If you look at the last figure here:

they don’t connect the fonebridge directly to the PBX servers. it is connected to the switch. Anyway I will get a quad-port NIC for each server.

Do you think the model: 750-4000-EC is suitable for my redundancy setup (2 servers) and 1 E1 line?

I am only concerned about documentation. For instance here: they don’t mention the 750-4000-EC model for the instructions.

What is your experience so far with this product? Ease of installation, support, voice quality, etc?

You are correct: the fonebridge replaces the internal TDM cards

3 NIC ports … sometimes 4:

(1) LAN …connection to internal extensions
(2) DRBD
(3) TDMoE … to fonebridge
(4) Optional … connection to WAN

Thanks mudslide567 for your reply.

How does the Redfone device work? I mean, does it completely replace the 2 Digium TE121B cards or does it work as a bridge between them? I guess it replaces them since it got a T1/E1 port. In this case I need more ports on each server:

1- for the LAN
1- for connecting the 2 servers for HA
1- Or both servers find the redfone on the LAN? Then I don’t need this 3rd port.

I will search more, but your help would put me up to speed.

The call center will be working 24 x 7, but I still need them to tell me about their recording retention policies since they hadn’t planned it yet.


(1) if you are using E1 for an HA setup, I would opt for the free standing Red-fone fonebridge device otherwise when you fail over, the E1 lines have to some how be manually dealt with whereas the fonebridge can be automated to follow the active server.

(2) you do not mention whether this is 30 seat running 24 x 7 or running business hours only. depending on the call volume and your recording retention policies, you could find yourself needing terabytes of storage for recordings. I have done a number of larger call centers with this type of setup and i think somewhere around that size, there is an economic tipping point where it becomes easier to manage and more economical to take the two servers and connect them to a DELL CX4 fiber array for the recording repository.

(3) don’t forget to install a good metrics and management package!