diff --git a/lib/call-session.js b/lib/call-session.js
index dd5966f..1c58047 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -758,7 +758,7 @@ Duration=${payload.duration} `
         }
       }
       else if (dlg.type === 'uac' && ['application/dtmf-relay', 'application/dtmf'].includes(contentType)) {
-        const arr = /Signal=\s*([1-9#*])/.exec(req.body);
+        const arr = /Signal=\s*([0-9#*])/.exec(req.body);
         if (!arr) {
           this.logger.info({body: req.body}, '_onInfo: invalid INFO dtmf request');
           throw new Error(`_onInfo: no dtmf in body for ${contentType}`);