ATM is a SONET based service which uses Asynchronous Transport Mode service access as its delivery platform. ATM service uses a high speed, cell-based, connection oriented transport technology to carry digitized voice, video, and data between end user locations. ATM service is established in two parts. First, the transport pipe is provisioned. This is a unstructured facility between the end user and the ATM switch. This transport pipe is called the User to Network Interface (UNI).

The UNI can be provisioned in three different speeds:

DS1 (1.544Mbps)

DS3 (45 Mbps)

OC3C (155 Mbps)

The second part is the Permanent Virtual Connection (PVC). PVCs are logical connections with in the physical facility. PVCs do not have any physical cross connections and do not require facilities of their own. PVCs can be ordered at various speeds ( e.g. 5Mbps, 10Mbps, etc.).