adapter and is received by the fr phy layer 40 which conveys it to the frame formatting element 42 like in the above described pvc case the frame formatting element 42 performs such functions as stripping off the beginning flag 62 and ending flag 70 and performing any error correction based upon the fcs 68 the t1 618 field 64 address and the user data field 65 are passed to the servicing element 50 the servicing element 50 first examines the address field 64 and based upon the dlci value the servicing element 50 knows that the user data field has an svc command in other words the dlci has an agreed upon value for instance the dlci may be the terminal adapter 39 s dlci the servicing element 50 then examines the command field 67 during the call set up procedure the command field 67 will have the value of the call set up command the servicing element then examines the parameters field 69 to obtain the destination dte 39 s e 164 address qos aal type etc based upon these values the servicing clement 50 builds pdus to be conveyed to the atm aal element 48 for atm adaptation layer processing these.