Hi Jithin,
Yes, the 7800 series phones support LLDP-MED (check out the following link).
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/7800-series/3pcc/11-0-1/english/adminguide/pa2d_b_7800-mpp-ag-11/pa2d_b_7800-mpp-ag-11_chapter_011.html
Here is an example for the "sh lldp" output of a 2960X switch with a 7841 attached.
2960X-SWITCH#sh lldp neighbors gigabitEthernet 1/0/5 detail
------------------------------------------------
Local Intf: Gi1/0/5
Chassis id: 172.16.14.3
Port id: 0051DCC5A4FD:P1
Port Description: SW PORT
System Name: SEP0051DCC5A4FD.example.com
System Description:
Cisco IP Phone 7841, V1, sip78xx.11-5-1-18.loads
Time remaining: 129 seconds
System Capabilities: B,T
Enabled Capabilities: B,T
Management Addresses:
IP: 172.16.14.3
Auto Negotiation - supported, enabled
Physical media capabilities:
1000baseT(FD)
100base-TX(FD)
100base-TX(HD)
10base-T(FD)
10base-T(HD)
Media Attachment Unit type: 30
Vlan ID: - not advertised
MED Information:
MED Codes:
(NP) Network Policy, (LI) Location Identification
(PS) Power Source Entity, (PD) Power Device
(IN) Inventory
H/W revision: 1
F/W revision: sboot2.78xx.11-5-1-18.sbn
S/W revision: sip78xx.11-5-1-18.loads
Serial number: XXXXXXXXXX
Manufacturer: Cisco Systems, Inc.
Model: CP-7841
Capabilities: NP, PD, IN
Device type: Endpoint Class III
Network Policy(Voice): VLAN 98, tagged, Layer-2 priority: 5, DSCP: 46
Network Policy(Voice Signal): VLAN 98, tagged, Layer-2 priority: 4, DSCP: 32
PD device, Power source: PSE, Power Priority: Unknown, Wattage: 3.6
Location - not advertised
Total entries displayed: 1
