【Network】BLF Not Showing Correct Status When Using DNS-SRV
Last modified date: 2020/12/29 Views: 2483

Yealink phone supports two kind of server redundency-failover and fallback. Please find related explaination about this on Page 205 of Administrator Guide below:
Yealink SIP-T2 Series T4 Series T5 Series CP920 IP Phones Administrator Guide V85.1
If the primary server fails, the phone will register to the backup server, and also subscribe for the BLF keys on the backup server as well.  When the primary server comes back online, the phone will register back to the primary server, but the BLF subscriptions remain on the backup server until reboot. 


When Primary comes back, phone will re-register to Primary after one expire. But phone will still subscribe BLF status to Secondary. Because the server address refers to the IP address provided in Contact header of the 200 OK message (like “Contact: <sip:200@>; expires=300). In this case, phone registers and subscribes to different serves and that cause the BLF not sychronized issue. ” 


This is the redundancy machenism applied on all Yealink phones and it is part of RFC. 



To solve this issue, we suggest you to use Fallback-Successive mode. 

##1-Successive registration, 0-Concurrent registration(default value)## 

##Time interval for phone to detect wehther the working server is available or not## 

account.X.sip_server.1.address= Yealink-2.Yealink.com   
##the IP address or domain name of the SIP server in which the account is registered.## 

account.X.sip_server.2.address = Yealink-3.Yealink.com 

More Information

If you need further information or support, please feel free to contact Yealink FAE for further support by ticket.yealink.com .

Product Type
VP59 , T58A with Camera , SIP-T58A , SIP-T57W , SIP-T54W , SIP-T53W , SIP-T53 , SIP-T48S , SIP-T46S , SIP-T42S , SIP-T41S , SIP-T40G , SIP-T40P , SIP-T29G , SIP-T27G , SIP-T23G , SIP-T23P , SIP-T21(P) E2 , SIP-T19(P) E2 , SIP-T33P(G) , SIP-T31(P)(G) , SIP-T30(P) , W90 Multi-Cell System , W80 Multi-Cell System , W60P , W53P , W56P , W52P , T54W with DD10K , W41P , W59R , VP530 , SIP-T38G , SIP-T32G , SIP-T28P , SIP-T26P , SIP-T22P , SIP-T21P , SIP-T20P , SIP-T19P , SIP VP-T49G , SIP-T48G , SIP-T46G , SIP-T42G , SIP-T27P , SIP-T41P
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