Other Credit Card Programs - How long befor unactivated credit card expires?

I am expecting some credit cards in the mail, but am leaving the country for a month. Can I activate them when I return or do they automatically cancel if not activated with some timeframe?

I am fairly certain that I have received cards, never activated, and received replacements a couple years later when the cards reached their expiration date. A month should not be a problem, but if you are concerned I would contact the issuers now to explain.

I am fairly certain that I have received cards, never activated, and received replacements a couple years later when the cards reached their expiration date. A month should not be a problem, but if you are concerned I would contact the issuers now to explain.

had a discover card for 4 or 5 years that was never activated.
they eventually cancelled it on me this year (probably trying to reduce their absolute risk).

they cancel when the card itself expires. although for my bank of america card, they sent me a new one when my unactivated card expired.

I've let them sit without activating for a year or more.