旅行券って英語でなんて言うの？

This appears to be a Travelers cheque Travelers check Cheque is British spelling and check is American spelling. Normally these are notes that can be exchanged for money at any major bank. It can be safer than carrying cash when travelling. Most major banks issue a form of travelers cheque, which is secured against loss, theft or damage. Each cheque carries a unique serial number. I hope that helps!

A "voucher" is a piece of paper that may be used at a business in exchange for goods or services. "Coupon" carries a similar meaning. This means a piece of paper exchanged for a discount, goods, or services. In this particular case, we say "travel voucher" or "travel coupon" to specify use with a travel agency. It is ultimately up to the speaker which word to choose, and the meaning is interchangeable.

A way of paying for something abroad.

Some companies issue vouchers which are designed to be given away in marketing promotions, or to be purchased in order to give them as gifts. Other companies, when they sell a holiday to someone, may give a voucher to the customer as a marketing incentive. If you go on a cruise, for example, you may be given 'onboard credit' which may be in the form of a voucher.

Gift Tokens are issued by companies as way of building some kind of LOYALTY with clients and customers...When it comes to spending / using these "VOUCHERS" the users will have limited options on where and when we can "CASH THEM IN!"

A travellers cheque is a form of money that can be used when abroad instead of carrying money you use the vouchers instead which you pay for in advance A travel voucher is a voucher given to you for the value of a certain amount of money

"Travel voucher" A voucher is something that can be used to buy things for a cheaper price. When you use a travel voucher you will receive a discount of some sort using this instead of paying it all with your own money.