Vehicle telematics connection retry

A method of re-establishing a cellular connection between a vehicle telematics unit and a wireless carrier system, comprising the steps of:

• (a) detecting a loss of cellular connection between a vehicle telematics unit and a wireless carrier system;
• (b) defining a re-connection period, during which time the vehicle telematics unit will attempt reconnection to the wireless carrier system, by the length of time a vehicle battery can provide power to the vehicle telematics unit;
• (c) accessing a technology order table (TOT) that orders a plurality of radio access technologies (RATs) capable of use at the vehicle telematics unit according to desirability;
• (d) attempting to re-establish the cellular connection by:
• (d1) determining the RAT used by the vehicle telematics unit when the loss of cellular connection was detected;
• (d2) searching the TOT to locate a less desirable RAT relative to the RAT used by the vehicle telematics unit when the loss of cellular connection was detected;
• (d3) attempting to connect with the wireless carrier system using the less desirable RAT and a group of PLMNs that is limited to home and home-equivalent PLMNs;
• and
• (d4) if step (d3) fails, attempting to connect with the wireless carrier system by iterating through each of the RATs ordered in the TOT beginning with a next less desirable RAT and including in the iteration the RAT used by the vehicle telematics unit when the loss of cellular connection was detected, wherein step (d4) uses all non-forbidden PLMNs until the re-connection period ends.