SIP-T21P and SIP-T22P Registration problem in Tunnels

[parscon]

Hello . Dear Support ,
I have 40 SIP-T21P and 23 SIP-T22P and 3 W52P in our offices but in 2 different locations that connected these office with PPTP tunnel with mikrotik routers.
also i have backup for my tunnels that if one tunnel will be disconnect backup tunnel will be up and when backup tunnel will be up all my yealink phones will be unregistered except W52P and also i have some grandstream phones . and when reboot the SIP-T21P and SIP-T22P they will not be register or if i reboot routers they will not register and only working solution is , i must change network of phones , that mean if they are in DHCP i must give them Static IP Address and if they are in Static IP Address mode i must change to DHCP and they will be work and phones will be registered again.
this is very strange problem please help me.
Note: i do not have a problem with Grandstream IP phone.
Note: i use zoiper softphone and also there is not any problem with it on changing the Tunnels.

I have another question that is there any option to connect with SSH or telnet to SIP-T21P and SIP-T22P ?

[James_Yealink]

Hello,

What's the firmware of the T21P and T22P?
Have you tried setting the "Server Expire" under account interface to a short value like 60 and check again?

To the second question, T21P and T22P can't not be connected through telnet or SSH.

Regards,
James

[parscon]

The version is 34.72.0.75 and also i tired setting the server expire . the problem is not registration , must change network setting that mean if it is DHCP must change to Static IP Address and if Static IP Address must change to DHCP after that will start to work . i do not have any problem with grandstream Phones . just this problem happen in yealink and i do not want to change all my phones . and also really it is hard every time change network setting phone ? so whats your solution for this Big Problem ?