Yealink T46G Administrator's Manual page 400

Yealink Skype for Business HD IP Phones Administrator Guide
User A places User B on hold.
3.
User A
F9. INVITE B (sendonly)
386
Proxy Server
F1. INVITE B
F4. 180 Ringing
F6. 200 OK
F7. ACK
2-way RTP channel established
F12. 200 OK
F13. ACK
No RTP packets being sent
F2. INVITE B
F3. 180 Ringing
F5. 200 OK
F8. ACK
F10. INVITE B (sendonly)
F11. 200 OK
F14. ACK
User B