Would like to ask in which domain you've worked with primarily in your 4 yrs experience?
If there's not been a particular domain, it's high time you attach utmost importance to it and going by that criteria off course telecom domain (my guess is the work will be in billing related applications and the company would likely be a mid to large size one) would be comparatively more beneficial than gaming but still even telecom is not the most sought after domain there is.
Try to scout for jobs in finance domain if you can or opt for telecom company's offer if you must change the job now.
Gaming company is also likely to be smaller in size and more prone to market fluctuations thereby likely making the job less stable.
If you are in a large size services company, why not ask for onsite opportunities in your current company itself and gaining an invaluable exposure with a prominent client abroad? You can always leave the job there no