Is change of sponcer/employer possible before visa issue, afater H1B petition?

[koriarguy]

A friend of mine was issued with an Approval Notice by US Citizenship immigration Services, by a company in the US, for his H1B (Petition type: I129 Petition for Non-immigrant Worker). It states it is valid from October 2014 to August 2017. He is an IT guy, with bachelors in Engineering from India (and with an additional 1 year diploma in Animations) and working in the field for the last 4 to 5 years and considered to be high value professional in his field. During the visa interview at the US consulate, he could not answer certain questions (he did not take help of an agent or representative but decided to manage it himself at that time) and his visa issuing is still pending. The company in the US is not very helpful (or not able to help?), then onwards.
My question is, once the application for H1B is approved for the candidate, stating that he is eligible for H1B visa (or selected as a candidate), is it possible to change the employer? Is it legal? If so, how to proceed with it? We will be interested to hear from potential employers, agencies, professionals, regarding taking forward his application.
Any informed information/response will be highly appreciated. Is it quite usual that this happens?

Thanks in advance.
KoriarGuy

[shervin143]

Any other U.S employer can file a new H1B petition using the CAP from the previous approval notice (meaning, a new petition need to be filed by the new employer that is CAP exempt). Once that petition gets approved, your friend can go for visa stamping again assuming the current visa application gets rejected (If the currently applied visa is still pending by that time, then he will need to withdraw the visa application). If the visa gets approved at that time, then he can travel with the H1B visa and new employer's approval notice to start working in H1B status for that employer.