diff --git a/CHANGELOG.md b/CHANGELOG.md
index 19c5b5d..b32fdd7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Change Log
 
+## [v4.20.1](https://github.com/plivo/plivo-node/tree/v4.20.1) (2021-07-27)
+- Updates to [add a member a multi-party call API](https://www.plivo.com/docs/voice/api/multiparty-call/participants#add-a-participant).
+  - Remove validation range for `delay` and `ringtimeout` parameters.
+  - Add appropriate error message for multiple `ringtimeout` and `delaydial` values.
+- Updated default HTTP client request timeout to 5 seconds.
+
 ## [v4.20.0](https://github.com/plivo/plivo-node/tree/v4.20.0) (2021-07-13)
 - Power pack ID has been included to the response for the [list all messages API](https://www.plivo.com/docs/sms/api/message/list-all-messages/) and the [get message details API](https://www.plivo.com/docs/sms/api/message#retrieve-a-message).
 - Support for filtering messages by Power pack ID has been added to the [list all messages API](https://www.plivo.com/docs/sms/api/message#list-all-messages).
diff --git a/lib/resources/multiPartyCall.js b/lib/resources/multiPartyCall.js
index 0fe35c6..3fee3f8 100644
--- a/lib/resources/multiPartyCall.js
+++ b/lib/resources/multiPartyCall.js
@@ -106,24 +106,24 @@ export class MultiPartyCall extends PlivoResource{
 
     if(params.ringTimeout || params.ringTimeout === 0){
       validParam('ringTimeout', params.ringTimeout, [String, Number], false)
-      if(Number.isInteger(params.ringTimeout)){
-        validRange('RingTimeout', params.ringTimeout, false, 15, 120)
-      }
-      else{
+      if(typeof(params.ringTimeout) === 'string'){
         validMultipleDestinationIntegers('ringTimeout', params.ringTimeout)
       }
+      else if (!Number.isInteger(params.ringTimeout) && typeof(params.ringTimeout) !== 'string'){
+        throw new InvalidRequestError("RingTimeout must be of type int or string")
+      }
     }
     else {
       params.ringTimeout = 45
     }
     if(params.delayDial){
       validParam('delayDial', params.delayDial, [String, Number], false)
-      if(Number.isInteger(params.delayDial)){
-        validRange('DelayDial', params.delayDial, false, 1, 120)
-      }
-      else{
+      if(typeof(params.delayDial) === 'string'){
         validMultipleDestinationIntegers('delayDial', params.delayDial)
       }
+      else if(!Number.isInteger(params.delayDial) && typeof(params.delayDial) !== 'string'){
+        throw new InvalidRequestError("Dealydial must be of type int or string")
+      }
     }
     else {
       params.delayDial = 0
@@ -306,6 +306,12 @@ export class MultiPartyCall extends PlivoResource{
     else {
       params.exitSoundMethod = 'GET'
     }
+    if(params.to && (String(params.ringTimeout).split('<').length > params.to.split('<').length)){
+      throw new MPCError("RingTimeout:number of ring_timeout(s) should be same as number of destination(s)")
+    }
+    if(params.to && (String(params.delayDial).split('<').length > params.to.split('<').length)){
+      throw new MPCError("DelayDial:number of delay_dial(s) should be same as number of destination(s)")
+    }
     params.isVoiceRequest = 'true';
     params.callerName = params.callerName || params.from;
     return super.executeAction(this.id + '/Participant/', 'POST', params)
diff --git a/lib/rest/axios.js b/lib/rest/axios.js
index 5316274..ba74448 100644
--- a/lib/rest/axios.js
+++ b/lib/rest/axios.js
@@ -175,6 +175,9 @@ export function Axios(config) {
     if (typeof config.timeout !== 'undefined') {
       options.timeout = config.timeout;
     }
+    else if(typeof config.timeout === 'undefined'){
+      options.timeout = 5000;
+    }
 
     return new Promise((resolve, reject) => {
       if (isVoiceReq) {
diff --git a/lib/rest/utils.js b/lib/rest/utils.js
index 8a7538c..934836c 100644
--- a/lib/rest/utils.js
+++ b/lib/rest/utils.js
@@ -115,17 +115,7 @@ export function validMultipleDestinationNos(paramName, paramValue, options = {})
 export function validMultipleDestinationIntegers(paramName, paramValue){
   let val = paramValue.split("<");
   for (let i=0; i<val.length; i++){
-    if (!isNaN(val[i]) && Number.isInteger(parseFloat(val[i]))){
-      if(paramName=="delayDial"){
-        if(val[i]!='0'){
-          validRange('DelayDial Destination Value', parseInt(val[i]), false, 1, 120);
-        }
-      }
-      else if (paramName=="ringTimeout"){
-        validRange('RingTimeout Destination Value', parseInt(val[i]), false, 15, 120);
-      }
-    }
-    else{
+    if (!(/^-?\d+$/.test(val[i]))){
       throw new InvalidRequestError( paramName + " Destination value must be integer");
     }
   }
diff --git a/package.json b/package.json
index d429fd9..a287d5d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "plivo",
-  "version": "4.20.0",
+  "version": "4.20.1",
   "description": "A Node.js SDK to make voice calls and send SMS using Plivo and to generate Plivo XML",
   "homepage": "https://github.com/plivo/plivo-node",
   "files": [