You missed phone specification, isn't it ? :
Ethernet switch | 10/100 PC switch port enables LAN connectivity to a co-located PC |
Phone have 10/100BaseT ports only, there's no 1000BaseT port at all.
Remember - 100BaseT doesn't mean you can pass 100Mbps of user data thru it. It's just link speed. Download/upload speed of user data will be noticeably lower. Ask your local network guru for explanation.