Is paying money to employees to facilitate obtaining a phone line for a commercial shop, after it was impossible to do so without payment, considered a bribe that necessitates sin?

The forbidden bribe is that which is paid to invalidate a right or establish a falsehood. As for what is paid to attain a right or repel injustice, it is permissible according to the majority of scholars. If you are certain of your entitlement to the job and there is no one more deserving than you, then it is permissible to pay money if it is absolutely necessary. However, if you have no right to it or someone else is more deserving, then paying money in this case is considered a forbidden bribe.