Hi All,
I am getting Session invalid or session expires error when i am caaling one saleforce org from another salesforce org.
here my code for callout.

String content = '{"Name": "Some acoount", "Phone":"9742882954"}';
     HttpRequest req = new HttpRequest();
     req.setEndpoint('https://ap1.salesforce.com/services/apexrest/Accountacc');
     req.setMethod('POST');
     
     String username = 'sarvesh01@gmail.com';
     String password = 'parvati@3';
 
     Blob headerValue = Blob.valueOf(username + ':' + password);
     String authorizationHeader = 'BASIC ' +
     EncodingUtil.base64Encode(headerValue);
     req.SetBody(content);
     req.setHeader('Content-Type', 'application/json; charset=utf-8');
     req.setHeader('Authorization', authorizationHeader);
     req.setHeader('Authorization', 'OAuth '+UserInfo.getSessionId());    
     Http http = new Http();
     HTTPResponse res = http.send(req);
     System.debug(res.getBody());


my rest class in another salesforce org.
@RestResource(urlMapping='/Accountacc/*')  
 global with sharing class callAccount {  
  
  @HttpPost  
   global static String doPost() {  
         
     RestRequest request = RestContext.request;  
     RestResponse response = RestContext.response;  
     String jSONRequestBody=request.requestBody.toString().trim();  
     Account accObj = (Account)JSON.deserializeStrict(jSONRequestBody,Account.class);  
     insert accObj;  
     return accObj.Id;  
   }  
  @HttpGet  
   global static Account doGet() {  
   
     RestRequest request = RestContext.request;  
     RestResponse response = RestContext.response;  
     String accountId = request.requestURI.substring(request.requestURI.lastIndexOf('/')+1);  
     Account acc= [SELECT Id, Name, Phone, Website FROM Account WHERE Id = :accountId];  
     return acc;  
   }  
 }


Can any one help me out please........
Thanks,
sarvesh.