Specifications

Chapter 10 – Internet Service Commands
Multi-Tech Systems, Inc. AT Commands for EDGE (E1) Modems (S000474A) 146
• The AT^SISI command shall be used to monitor the progress of the session. The command reports the
service state of the used service profile and indicates the number of bytes received, the number of bytes
sent and, in the case of sending, the number of bytes acknowledged or unacknowledged at TCP layer.
• If an error occurs during a session you can enter the AT^SISE command and the <srvProfileId> to identify
the reason. This is especially important in polling mode.
• Finally, to end a session, enter the AT^SISC write command and the <srvProfileId>.
Additional AT commands designed for controlling and monitoring the connection profiles (bearers):
• The AT^SICI command can be used any time to query the current status of one or all connection
profile(s).
• The AT^SICO command opens a connection and keeps it open until closed with AT^SICC or
disconnected
• by the network.
• The AT^SICC command closes a connection set up with AT^SICO.
• The AT^SISX command sends ICMP (Internet Control Message Protocol) Echo Requests to a target IP
address or host name to verify the TCP/IP network connection.
Maximum number of profiles defined / used:
• Up to 6 connection profiles can be created (with AT^SICS).
• Up to 10 service profiles can be created (with AT^SISS), but the number of parallel profiles of the same
service type is limited as listed below. If the maximum number of a service profile type is already defined,
any attempt to set up another profile for the same type will be denied with “+CME ERROR: operation of
service temporarily not allowed”.
∗ Maximum 3 HTTP profiles
∗ Maximum 6 socket profiles: Only two instances can be opened for the listener. This means that if
two listeners are established another four instances can be opened for clients. Also, the socket
service can accept an incoming connection only when at least one service profile is still free (not
yet created with AT^SISS); otherwise, the incoming connection will be closed to the listener. If there
is no listener established, all six socket profiles can be configured as Client.
∗ 1 FTP profile
∗ 1 POP3 profile
∗ 1 SMTP profile
• The TCP/IP stack of Multi-Tech Wireless EDGE modem supports using several service profiles at the same
time, provided all of them are running on the same connection profile. For example, it is possible to
download files from an FTP server, while sending and receiving emails at the same time.
Address Notation:
Server addresses must be provided as IP addresses in standard dot-format (e.g., “192.168.1.2”) or as server
address names resolvable by a DNS server (e.g., “smtp.myserver.de” or “pop3.myserver.de”).
Inactivity Timeouts:
Inactivity timeouts are not part of the Internet AT command functionality implemented with Multi-Tech wireless
modem and, if desired, are the responsibility of the host application. It is recommended that the host application
validates URCs and AT command responses and reacts adequately. Example: Sending a close message or a
starting timer.
Socket service used with UDP protocol
The significant differences between the TCP and UDP protocols imply that UDP sometimes requires particular
procedures or even specific parameters. Details on how to handle UDP services can be found in extra notes or
are included in the general parameter descriptions.
The EDGE wireless modem offers two kinds of Socket service with UDP protocol. One is referred to as UDP
client intended for connections to a given remote host. In this case the IP address and the UDP port of the
remote host are set as a fixed parameter in the service profile. The other type is referred to as UDP endpoint
where IP address and UDP port of the remote hosts are handled in each read (AT^SISR) and write (AT^SISW)
request. This enables the host application to communicate with different remote hosts.
Using the DCD line to detect the connection status of Internet services
With AT&C you can configure the DCD line of the used serial interface to indicate whether an Internet service is
active. For Socket, HTTP, SMTP and POP3 the states "Up" or "Connecting" are indicated, for FTP only the state
"Up".