1. It looks like the UC560 can support dual PRI's, but the UC540 may not be able too. (It looks like it doesn't support the dual port card -- and may not have enough DSP resources anyway)
2. What do you mean by 4 "voip lines"? If you mean 4 separate SIP trunks -- the UC500 only "officially" supports 1 SIP trunk. Although the router is capable of more, the tool used for configuration (CCA) only supports one.
3. Both the 540 and 560 come with 30 user licences out of box.
Thank you for and answer Daniel, by 4 lines I meant to handle 4 phone calls at once. Would you recommend anything else? like SPA or RVS? I am not very familiar with voice but it is going to be installed in our company so I can afford to make some mistakes when installing it.
Honestly I would recommend you work with a Cisco Partner or qualified consultant... these systems are not designed for the end-user to self-install and you will likely be very frustrated if you attempt to do so..
That aside, these are the systems that fit your requirements: (based on what little information you gave us anyway)
2. Call-Manager Express (ISR G2 Routers)
3. Business Edition 3000 (Still a very new product -- some feature holes)
I would probably recommend CME + CUE on a 2901 ISR. It sounds like you might be frustrated with the configuration limitations of the UC500 if you go that route.
I don't think anything in the SPA line would work for you, and your system is to small to justify BE6000 or full Call-Manager.
The UC540 would be perfect IMO. Find a good SIP provider and your only limited by bandwidth and the number of DID's and I guess DSP resources but at 15 users I wouldnt worry to much about that. CCA is much improved now compared to what it was a few years ago and you should be able to get it up and running pretty quickly. There are tons of resources under the technical enablement labs for the UC5xx/SBCS product line. We did a roadshow the last quarter of 2010 and used most of those labs (the ones in under the technical enablement labs page) to show partners all the ins and outs of the UC500 product line and I know during the ones I did I had a ton of Account Managers who felt confident enough to actually do the technical install of a basic system after a few days of training. Cisco is dedicated to making sure their partners and their customers have every tool possible to be successful so use them!
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