You are describing one scenario where this invention could be used ("a system that calls 911 when it detects a crash").
The legal protection provided by this patent is _not_ limited to any specific context or scenario.
Let's take '707 claim 6. _Any_ commercial product with each and every one of the following bullet points ("limitations" in lawyer-speak) infringes and must purchase a license to this patent.
[1] A vehicle, comprising:
[2] a factory-installed first apparatus configured to generate an electrical signal;
[3] a factory-installed second apparatus configured to receive the electrical signal; and
[4] a retrofit apparatus electrically connected to the factory-installed second apparatus,
[5] wherein the retrofit apparatus generates a mimicked electrical signal independently of the electrical signal generated by the factory-installed first apparatus, and
[6] wherein the factory-installed second apparatus receives the mimicked electrical signal.
Let's take '707 claim 6. _Any_ commercial product with each and every one of the following bullet points ("limitations" in lawyer-speak) infringes and must purchase a license to this patent.
[1] A vehicle, comprising: [2] a factory-installed first apparatus configured to generate an electrical signal; [3] a factory-installed second apparatus configured to receive the electrical signal; and [4] a retrofit apparatus electrically connected to the factory-installed second apparatus, [5] wherein the retrofit apparatus generates a mimicked electrical signal independently of the electrical signal generated by the factory-installed first apparatus, and [6] wherein the factory-installed second apparatus receives the mimicked electrical signal.