I'm having an issue with transfering SIP calls from one UA to another with Mikrotik HAP AC router. There is no problem with blind transfers. We only have problems with attended transfers. Terminal A established a session with terminal B. Terminal B puts terminal A on hold. Terminal B calls terminal C to announce the transfer and puts terminal C on hold. Terminal B trasnfers terminal C to terminal A. Terminal A replaces the session between B and C, but INVITEs don't progress. Terminal C does not receive the INVITEs.