DTMF fails with "GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: Rejected send message"

Full error message:

** (sm.puri.Calls:6658): WARNING **: 12:42:57.383: Error sending DTMF ModemManager call to `07763578094':
GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: Rejected send message, 2 matched rules; type="method_call"
sender=":1.1517" (uid=1000 pid=6658 comm="./proj/dialer/calls-build/src/calls ")
interface="org.freedesktop.ModemManager1.Call" member="SendDtmf" error name="(unset)"
requested_reply="0" destination=":1.4" (uid=0 pid=343 comm="/usr/sbin/ModemManager --filter-policy=strict ")