Maintaining speed after teleportation [c#]

In my game i have portals that the player can walk through and i want him to maintain his speed like if he falls. How do i do that? script: public GameObject otherPortal; void OnTriggerEnter(Collider other) { Debug.Log ("something hit the portal"); other.transform.position = otherPortal.transform.position + otherPortal.transform.forward * 1; other.transform.rotation = otherPortal.transform.rotation; }