What is difference between 2821 and 2811 router for VoIP lab?

[eigrpy]

Hi I want to set up a VoIP lab. But I want to replace router 2821 with 2811. If so, what function I will lose? Thank you

[Manish Gogna · Accepted solution]

In terms of voice features there is basically no difference between these two. You can check their datasheets or comparison charts like below for details

http://www.cisco.com/c/en/us/products/routers/2800-series-integrated-services-routers-isr/models-comparison.html

Manish

[shiblyibrahim · Accepted solution]

If its CME or SRST you will find a difference in the number of phones you can support.

[eigrpy]

Thank you so much for your reply. 

You can check their datasheets or comparison charts like below for details

It looks like the the data sheet shows 2821 has 3 Onboard DSP Slots, and 2811 has 2

What is Onboard DSP Slots?

[Ryan Huff]

You'll also gain 1 RU.