Gilbert is dissatisfied with his phone because it has a very short battery life. He realizes that he needs a phone that has a longer battery life. Gilbert is in the stage of the consumer decision-making process

- Problem-recognition.

Explanation:

The consumer decision-making process is associated with the process of consumers recognizing their needs and requirements, collecting information followed by the evaluation of distinct alternatives available in the market and then finally reaching a decision to opt for a specific product to buy.

As per the given description, Gilbert's evaluation of his need that his current phone is not able to meet up his requirement and realization that he requires a phone with a longer-battery life exemplifies that he is in the 'problem-recognition' phase of the consumer decision-making process. This stage would be followed by the assessment of alternatives(various phones with longer battery life) and reaching the conclusion to buy a specific chosen product after the evaluation.

Problem recognition

Explanation:

Problem recognition is the stage in the consumer decision-making process that helps the customer to recognize the difference between the actual state and the wanting state.

In the given case, Gilbert recognized his actual state in which his mobile's battery has a short life. This actual state of Gilbert led him to his wanting state in which he wants a phone with a longer battery life.

So, Gilbert is in the problem recognition stage of consumer decision making process.  

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