Why is VoIP registration interrupted with a Mikrotik router when WinBox is closed?

Question

VoIP

Starts to smell like magic or I'm going crazy. There is a Mikrotik, it distributes the Internet to the network in the router mode through the bridge. All devices on the network (computers, printers, network storages) work correctly. There is a Gigaset IP phone, registration began to break on it. But if you open winbox and run torch in the bridge interface (through which the Internet goes for an IP phone) with a filter by the IP address of this phone, then the registration is not broken.
What have you been doing.
1) Disabled all items in the firewall
2) Opened full access to the IP address of this phone in the firewall
3) Disabled the marking of its packets
4) Disabled/enabled SIP in the service ports in the firewall
5) Set the static/dynamic IP address in the phone
6) Assigned other IP addresses telephone
7) Changed DNS to Google, Yandex
When torch is disabled in winboxe, all these settings do not give any positive results
. If you enable torch in winboxe, then everything works correctly.
I took this phone home. At home, this phone works fine, the registration does not break, i.e. Mikrotik problem.

Where to dig?

Answer 1

1) Are the correct ports in ip-firewall-Service ports in the sip item? What is the timeout?
2) What is the registration timeout in the phone?
3) What timeout does the sip provider require?

Answer 2

Faced a similar problem, the VPN connection with the gigaset was torn, although locally everything was normal. I also noticed that if you start a ping from the microtic to which the gigaset is connected - everything works, as soon as you close the winbox or stop the ping - the connection breaks. I found a solution in the form of Netwatch which pings the address of the gigaset every second. The crutch is still the same - but working. With Panasonic, for example, this does not happen - everything works out of the box.