X25AM Programming Manual

Introduction

X25AM Programming Manual—527201-001

1-12

Call Request Packet

A Call Request packet is issued by X25AM in response to a CONTROL 17 procedure

(or a WRITE procedure for PTP mode 2, where the application builds its own call

request packet).

Called Address

The called address is the subdevice DESTADDR attribute, which may or may not

contain a port number. The called port number, if there is one, is transmitted in the

called address field or in the fifth byte of the call user data. The location of the port

number is determined by the subdevice attribute REMOTENET. Specific network

REMOTEIDs are listed in the X25AM Configuration and Management Manual.

Calling Address

The calling address is the line SRCADDR unless the line has been configured for a

NULL calling address. The port number can be appended to the line SRCADDR

(unless the application does not allow this and has issued a SETMODE 32). In some

cases, the calling address is only the port number. This depends on the line attribute,

NETID. Specific network NETIDs are listed in the X25AM Configuration and

Management Manual.

Facilities

The facilities length field is always included. For descriptions of supported facilities, see

Per Call Facilities on page 1-16.

Call User Data

A Call Request packet can reset the CUD values. For a detailed discussion of this field,

see Call User Data (CUD) in Call Setup Packets on page 1-7.

Call Connected Packet

In response to a Call Request issued by X25AM, the network returns a Call Connected

packet when the call can be completed. If the call cannot be completed, the network

returns a Clear Request.

Called and Calling Address

The called and calling addresses are ignored.

Facilities

The facilities field can be a maximum of 63 (1980 X.25 format) or 109 (1984 X.25

format) bytes. If the facilities field exceeds the maximum, the call is cleared. Unknown