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New Member

Upgrading to a 2851 vs 3825

I'm having a difficult time making a long term solution.

We join 2 buildings via 3 point to point T's, each building has 150 users. (Currently connected with 2 7206 models that are end of life)

With an eye to the future, for VoiP, is the 2851 sufficient for our needs?

I guess what I'm really saying, am I limiting my future options by selecting the 2851?

I can't reallt see the added benefit in the 3800 series.

Any thoughts or insight would be appreciated.

Hall of Fame Super Silver

Re: Upgrading to a 2851 vs 3825


I do not believe that you have given us sufficient detail to help us to give you a good answer. For 2 buildings, 3 point tot point T1s, and 150 users in each building then the 2851 ought to be enough. But what are your future requirements? How are things likely to grow? How are the requirements likely to change? Only if we know these things can we give advice about the 2851 or the 3800 series. In general the 3800 is a higher capacity box. It supports more interfaces, more memory, higher speed interfaces, higher traffic loads, etc. Only if you have some way to project your future requirements can you make an intelligent choice between these parts of the product line.



Hall of Fame Super Gold

Re: Upgrading to a 2851 vs 3825

To add to the good advice, the 3845 would support 144 ip phones in CCME mode, that is the feature in which router does a nice PBX with all the features. Also note, if your 7206 are VXR, they are not EOL at all, you can put an NPE-400 in it and they would keep doing a good job for many years again.

Hope this helps, pleas rate post if it does!

New Member

Re: Upgrading to a 2851 vs 3825

I truly appreciate the time to respond.

I do not anticipate significant growth at either location, physical space is what it is.

Internet and eMail servers are located at our main building. The second building accesses these servers/services across the routers. The second building has their own local file servers, it's only for email and internet at this time.

My eye to the future is in VoiP, a subject I have limited working knowledge. Whether the 2851 model would support the traffic of 300 IP phones.

The best I can tell, the 2851 will support everything we need, but I keep thinking I'm missing something, and later on I'm going to regret not making the larger investment for the 3800 series now.

For pure speed, which is not bad at all currently, both are clearly an upgrade to our exsiting 7206's. Furthermore, we can eliminate our exsiting multiplexors since we will be able to terminate the point to point T's directly to the new routers.

I'm leaning toward the 2851, a more cost effective solution, with 2 dual port WIC cards. Of course, this assumes im correct, and I will not be limiting my future VoiP options and both will handle the overall throughput.

Re: Upgrading to a 2851 vs 3825

The 2851 (from experience) will support 300 IP phones just fine.

Here's the real breakdown in difference --

2851's will handle T1 cards and such with no issues. However, the 3825/3845 were designed to support DS3/T3 interface cards with full services (thus the higher cpu/memory requirements).

Note -- 300 IP Phones at g729 (8Kb/s) = 2.4mbit/s (1.5x a T1). You need to keep in mind where the call flow will be, where your call manager will reside in order to do call setup/etc, and other important details. If you plan on doing SRST/CCME on this router, then you will only have 96 survivable phones in the event of a call-manager catastrophic failure.

There really is no reason for you to jump to a 3825/3845 unless you will really be expanding and jumping up to full-service DS3 services terminating on that router.