Voice Gateway Selection

[mightyking]

Hello Experts,

We are planning replacing our 2851 Cisco gateways. We are moving from ISDN PRI to SIP trunking very soon and need to buy the equipments allowing SIP trunking. We are a bit tight with the budget and was thinking to go with 3925 series.  I know 3925 gateways have CUBE capability and don't need to buy a second device for this fonctionality. Would that be a good choice knowing that 3925 has limited number of SRST per GW.

Thanks,

MK

[james-amenta]

I would think this depends on if the number of SRST per GW is enough for your needs.  As long as the 3925 offers enough SRST seats to accommodate your office then it's a good solution, but if you have more users than SRST seats you may want to go with another model.  Also, Cisco now sells used equipment that is still fully covered by SMARTnet.  Check out Cisco Refresh to see if they have gateways that are better suited for your needs at a price that fits your budget.

http://www.cisco.com/web/ciscocapital/refresh/index.html 

[mightyking]

Thanks guys,

How do we calculate how many RTU licenses we need? Let's say we are going with a 3925, how many licenses come with this router?

Thanks,

MK

[james-amenta]

I don't believe any licenses come with the router.  I would recommend that your licensing be equal to the number of concurrent calls you can handle with the connection.  For instance, if you have a SIP circuit from the phone company designed to handle 100 concurrent calls, you would need to license 100 concurrent calls within CUBE.  Your Cisco partner can help you with the exact counts and pricing, but if you don't buy enough CUBE licensing to match your circuit you won't be able to use the available SIP bandwidth.

[mightyking]

Thanks guys, it's really appreciated.

MK

[Chris Deren]

It's all based on number of concurrent calls you want to allow. Each platform scales up to certain max number of SIP sessions, see table 2 for the details:

http://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-border-element/data-sheet-c78-729692.html

[Chris Deren]

In addition keep in mind that you need to purchase CUBE licenses when converting to SIP trunk, these are RTU licenses tied to the specific router and not portable. So, if the goes is to at some point replace the CUBE router as 29XX are at some point going to be no longer supported, you may consider this since CUBE licenses are not cheap.