Hi. Am looking for a cheap alternative to IP dect so am looking at SIP cordless handsets to go onto an IPO500V2 on a pure IP system. Have the 3rd party end point licenses and have tried to register the Siemens gigaset 5080IP sip handsets with no success. Apparently the Avaya ATA a10 is no longer available so can't use that to support analogue dect handsets. Any suggestions re getting the Siemens handsets working or any other ata's out there that are available and proven?