TextMe users in the US can now place emergency calls by dialing 9-1-1 within the TextMe app.
By default, dialing 9-1-1 in the app will open your mobile phone's native dialer to connect to the local emergency dispatch. This will use your device's SIM card, regardless if you have a cellular plan through a network carrier plan or not.
If you use TextMe on a device without a SIM card, or your area receives poor/zero cellular signal, then you can switch the Native Dialer setting off. 911 calls will be routed directly through the TextMe App. In this case, it is recommended to fill out your emergency address ahead of time, to help confirm proper routing of the call. (This is necessary because without the SIM card there is no location information available to emergency services).