I have changed my router and my Aastra Telephone is not working

This is a common scenario I have found. At least, here in Canada, it is very common you change Internet provider if you find a better deal. So, if you have VoIP in your home or office, this means you will need to change your router (sometimes called modem).

For unlucky owners of Aastra telephones, you will notice your telephone won't work using the new modem. It seems there is a bug on the firmware, the only possible solution I have found is by doing a hardware reset of the telephone. Take note of your SIP credentials, because you will need to enter them; this could be a good opportunity to configure auto-provisioning if you have your own PBX (like FusionPBX).