{"id":1007,"date":"2026-09-22T09:41:24","date_gmt":"2026-09-22T09:41:24","guid":{"rendered":"https:\/\/smppcenter.com\/kb\/?p=1007"},"modified":"2026-09-22T09:41:26","modified_gmt":"2026-09-22T09:41:26","slug":"smpp-connect-extra-attributes","status":"publish","type":"post","link":"https:\/\/smppcenter.com\/kb\/smpp-connect-extra-attributes\/","title":{"rendered":"SMPP Connect Extra Attributes: Advanced Bind Tuning for Upstream Vendors"},"content":{"rendered":"\n

The standard SMPP Connect form covers most vendors. Some vendors need extra settings: TLS binds, a stricter keep-alive, a smaller in-flight window, or prefix restrictions. Extra Attributes<\/strong> lets you set these per connect without changing any other connect.<\/p>\n\n\n\n

Where to find it<\/h3>\n\n\n\n

SMPP Client \u2192 Connects<\/strong> \u2192 Edit<\/strong> the connect \u2192 scroll to the bottom \u2192 Extra Attributes<\/strong>. Choose an Attribute<\/strong>, enter a Value<\/strong>, and click Save Changes<\/strong>. Add one attribute per entry.<\/p>\n\n\n\n

Most useful attributes<\/h3>\n\n\n\n

Connection stability<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
enquire-link-interval<\/code><\/td>Seconds between keep-alive (enquire_link) packets. Lower it if the vendor or a firewall drops idle binds<\/td><\/tr>
reconnect-delay<\/code><\/td>Seconds to wait before re-binding after a disconnect. Increase it if the vendor blocks rapid re-binds<\/td><\/tr>
connection-timeout<\/code><\/td>How long to wait when opening the connection<\/td><\/tr>
wait-ack<\/code> \/ wait-ack-expire<\/code><\/td>How long to wait for a submit_sm_resp<\/code>, and what to do when it doesn’t arrive<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Throughput and flow control<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
max-pending-submits<\/code><\/td>Maximum unacknowledged submits in flight (the window). Lower it if the vendor throttles or disconnects under load<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Security<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
use-ssl<\/code><\/td>Bind over TLS when the vendor requires an encrypted SMPP port<\/td><\/tr>
ssl-client-certkey-file<\/code><\/td>Client certificate, if the vendor requires mutual TLS<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Addressing and filtering<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
allowed-prefix<\/code> \/ denied-prefix<\/code><\/td>Only send (or never send) numbers with these prefixes on this connect. A safety net against sending traffic to destinations the vendor doesn’t cover<\/td><\/tr>
preferred-prefix<\/code> \/ unified-prefix<\/code><\/td>Prefix preference and number normalisation for this connect<\/td><\/tr>
source-addr-ton\/npi<\/code>, dest-addr-ton\/npi<\/code>, bind-addr-ton\/npi<\/code>, source-addr-autodetect<\/code><\/td>Override TON\/NPI handling when the TON\/NPI tab isn’t enough<\/td><\/tr>
address-range<\/code>, service-type<\/code>, interface-version<\/code>, my-number<\/code><\/td>Vendor-specific bind parameters<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Message handling<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
validityperiod<\/code><\/td>Message validity sent to the vendor. Useful for OTP routes, so stale OTPs expire instead of arriving late<\/td><\/tr>
esm-class<\/code>, alt-dcs<\/code>, alt-charset<\/code>, alt-addr-charset<\/code>, max-sms-octets<\/code><\/td>Encoding and message-class adjustments for vendors with non-standard handling<\/td><\/tr>
msg-id-type<\/code><\/td>How the vendor’s message IDs are read (e.g. hex vs decimal). Fix this when DLRs don’t match their messages<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Diagnostics<\/strong><\/p>\n\n\n\n

Attribute<\/th>Use<\/th><\/tr><\/thead>
log-level<\/code>, log-format<\/code><\/td>More detailed logging on one connect while troubleshooting. Turn it back down afterwards<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Applying changes<\/h3>\n\n\n\n

Extra attributes are bind-level settings. After saving, reload\/reconfigure the connect from its Connection<\/strong> manager, and restart the Connect Manager<\/strong> (System \u2192 Controls \u2192 SMPP Client) if the change doesn’t take effect. Do this in a low-traffic window.<\/p>\n\n\n\n

Good practice<\/h3>\n\n\n\n