I installed the LTE router and connected my phone and legacy alarm system to the phone port with the telephony mode set to VOLTE. The phone works fine, but the alarm system, which uses DTMF tones to control can no longer be controlled. The alarm system can dial out, but when the call is answered, the DTMF tones used to manage it are not received. I tried setting the telephony mode to VOIP, but was not able to make or receive calls.