Our Vonage VoIP Phones were working with our old NetGear MBR1515A router. We recently took the same SIM Card out of the Netgear Router and put it in our new Digi Transport Modem. Our phones now recognize IP Addresses and firmware, but still read no service. We can also find them in attached devices on our Digi Modem.
Transport is connected to the internet.
are the phones getting address details from the transport?
are you saying the phones are getting firmware from the internet?
is the Service and internet service or corporate service are the phone correctly configured.
the transport has no special features for VOIP phones
If your Transport is using any firmware version above 126.96.36.199, VOIP or WiFi Calling does not work.
Edited post, the latest version 188.8.131.52 (Oct 3 2017 14:57:59) has addressed the issue (or a few versions previous?? but I haven’t tested to determine which)
So restated some versions above 184.108.40.206 will have issues, but problem is resolved at current version 220.127.116.11
Other than Vonage I am using virtual phone numbers to connect with business clients over the internet without using a Sim card.
The VoIP phone was having the issue just because it was having some kind of technical default just because it with digi transport was not able to work properly so windows 10 sound crackling it will guide you with the proper information.