support sending DTMF to caller (#125)

* support sending DTMF to caller

* wip

lib/call-session.js

@@ -780,6 +780,27 @@ Duration=${payload.duration} `
             )).every((r) => r);
           }
           res.send(succeeded ? 200 : 503);
+        } else if (reason.includes('Dtmf')) {
+          const arr = /Signal=\s*([0-9#*])/.exec(req.body);
+          if (!arr) {
+            this.logger.info({body: req.body}, '_onInfo: invalid INFO Dtmf');
+            throw new Error(`_onInfo: no dtmf in body for ${contentType}`);
+          }
+          const code = arr[1];
+          const arr2 = /Duration=\s*(\d+)/.exec(req.body);
+          const duration = arr2 ? arr2[1] : 250;
+          const dtmfOpts = {
+            ...this.rtpEngineOpts.common,
+            'from-tag': this.rtpEngineOpts.uac.tag,
+            code,
+            duration
+          };
+          const response = await this.playDTMF(dtmfOpts);
+          if ('ok' !== response.result) {
+            this.logger.info({response}, `rtpengine play Dtmf failed with ${JSON.stringify(response)}`);
+            throw new Error('rtpengine failed: answer');
+          }
+          res.send(200);
         }
       }
       else if (dlg.type === 'uas' && ['application/dtmf-relay', 'application/dtmf'].includes(contentType)) {

lib/utils.js

@@ -22,8 +22,8 @@ function makeRtpEngineOpts(req, srcIsUsingSrtp, dstIsUsingSrtp, teams = false) {
   const dstOpts = dstIsUsingSrtp ? srtpOpts : rtpCopy;
   const srcOpts = srcIsUsingSrtp ? srtpOpts : rtpCopy;
 
-  /* webrtc clients (e.g. sipjs) send DMTF via SIP INFO */
-  if ((srcIsUsingSrtp || dstIsUsingSrtp) && !teams) {
+  /* Allow Feature server to inject DTMF to both leg except call from Teams*/
+  if (!teams) {
     dstOpts.flags.push('inject DTMF');
     srcOpts.flags.push('inject DTMF');
   }