diff --git a/erpnext/accounts/doctype/payment_request/payment_request.py b/erpnext/accounts/doctype/payment_request/payment_request.py
index 7005c17362b..5f5647c7ecc 100644
--- a/erpnext/accounts/doctype/payment_request/payment_request.py
+++ b/erpnext/accounts/doctype/payment_request/payment_request.py
@@ -497,10 +497,16 @@ def get_amount(ref_doc, payment_account=None):
 	if dt in ["Sales Order", "Purchase Order"]:
 		grand_total = flt(ref_doc.rounded_total) or flt(ref_doc.grand_total)
 	elif dt in ["Sales Invoice", "Purchase Invoice"]:
-		if ref_doc.party_account_currency == ref_doc.currency:
-			grand_total = flt(ref_doc.outstanding_amount)
-		else:
-			grand_total = flt(ref_doc.outstanding_amount) / ref_doc.conversion_rate
+		if not ref_doc.is_pos:
+			if ref_doc.party_account_currency == ref_doc.currency:
+				grand_total = flt(ref_doc.outstanding_amount)
+			else:
+				grand_total = flt(ref_doc.outstanding_amount) / ref_doc.conversion_rate
+		elif dt == "Sales Invoice":
+			for pay in ref_doc.payments:
+				if pay.type == "Phone" and pay.account == payment_account:
+					grand_total = pay.amount
+					break
 	elif dt == "POS Invoice":
 		for pay in ref_doc.payments:
 			if pay.type == "Phone" and pay.account == payment_account: