A customer who has a complete setup of Snom SIP phones and some sort of hosted telephony service now want's to switch to an UC500 solution. Is there a way to reuse the current Snom phones with a UC500? If it's possible what sorts of drawback would there be instead of using Cisco phones?
Its not going to be supported and interoperability with Cisco SCCP phones is not going to be predictable. I dont recommend it. I would guess you would be upside down on costs after the first week of trying to deploy it. rather just buy the low cost Cisco SPA500 phones which operate in a tokenized SCCP protocol on UC500 called SPCP. There is also some investment protection here, since if they want to go the hosted SP route, these phones also operate SIP.
This is possible to do. You can look on cisco.com and find guides that use SIP phones.
The big problem is support. When using 3rd Party SIP phones, support will be difficult to find.