Yealink SIP-T2 SERIES Administrator's Manual page 968

Administrator's Guide for SIP-T2 Series/T19(P) E2/T4 Series/CP860 IP Phones
946
VP-T49G IP phones)
For ext keys:
Valid types are:
0-NA
1-Conference
2-Forward
3-Transfer
4-Hold
5-DND
7-ReCall
8-SMS
9-Direct Pickup
10-Call Park
11-DTMF
12-Voice Mail
13-Speed Dial
14-Intercom
15-Line
16-BLF
17-URL
18-Group Listening
20-Private Hold
22-XML Group
23-Group Pickup
24-Multicast Paging
25-Record
27-XML Browser
34-Hot Desking
35-URL Record
37-Switch (only applicable to ext key 1)
38-LDAP
39-BLF List
40-Prefix
41-Zero Touch
42-ACD
45-Local Group
50-Phone Lock