You can limit your calls/SMS to certain prefixes by following below instructions, below example shows how to allow calls & SMS only to the US.


Below are the prefixes for the US state:


1201, 1202, 1203, 1205, 1206, 1207, 1208, 1209, 1210, 1212, 1213, 1214, 1215, 1216, 1217, 1218, 1219, 1224, 1225, 1228, 1229, 1231, 1234, 1239, 1240, 1248, 1251, 1252, 1253, 1254, 1256, 1260, 1262, 1267, 1269, 1270, 1276, 1278, 1281, 1301, 1302, 1303, 1304, 1305, 1307, 1308, 1309, 1310, 1312, 1313, 1314, 1315, 1316, 1317, 1318, 1319, 1320, 1321, 1323, 1325, 1330, 1331, 1334, 1336, 1337, 1339, 1346, 1347, 1351, 1352, 1360, 1361, 1364, 1385, 1386, 1401, 1402, 1404, 1405, 1406, 1407, 1408, 1409, 1410, 1412, 1413, 1414, 1415, 1417, 1419, 1423, 1424, 1425, 1430, 1432, 1434, 1435, 1440, 1442, 1443, 1447, 1458, 1464, 1469, 1470, 1475, 1478, 1479, 1480, 1484, 1500, 1501, 1502, 1503, 1504, 1505, 1507, 1508, 1509, 1510, 1512, 1513, 1515, 1516, 1517, 1518, 1520, 1530, 1531, 1534, 1539, 1540, 1541, 1551, 1557, 1559, 1561, 1562, 1563, 1567, 1570, 1571, 1573, 1574, 1575, 1580, 1585, 1586, 1601, 1602, 1603, 1605, 1606, 1607, 1608, 1609, 1610, 1612, 1614, 1615, 1616, 1617, 1618, 1619, 1620, 1623, 1626, 1630, 1631, 1636, 1641, 1646, 1650, 1651, 1657, 1660, 1661, 1662,667, 1669, 1678, 1681, 1682, 1701, 1702, 1703, 1704, 1706, 1707, 1708, 1712, 1713, 1714, 1715, 1716, 1717, 1718, 1719, 1720, 1724, 1725, 1727, 1730, 1731, 1732, 1734, 1740, 1747, 1752, 1754, 1757,760, 1762, 1763, 1765, 1769, 1770, 1772, 1773, 1774, 1775, 1779, 1781, 1785, 1786, 1801, 1802, 1803, 1804, 1805, 1806, 1808, 1810, 1812, 1813, 1814, 1815, 1816, 1817, 1818, 1830, 1831, 1832, 1835, 1843, 1845, 1847, 1848, 1849, 1850, 1856, 1857, 1858, 1859, 1860, 1862, 1863, 1864, 1865, 1870, 1872, 1878, 1901, 1903, 1904, 1906, 1907, 1908, 1909, 1910, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1925, 1927, 1928, 1929, 1930, 1931, 1936, 1937, 1938, 1940, 1941, 1947, 1949, 1951, 1952, 1954, 1956, 1959, 1970, 1971, 1972, 1973, 1978, 1979, 1980, 1984, 1985, 1989


You will have to make sure you whitelist these prefix in your application.


If you wish to send messages to US Islands, you can whitelist the below prefixes as well


1242 ,1246 ,1264 ,1268 ,1284 ,1340 ,1345 ,1441 ,1473 ,1649 ,1664 ,1670 ,1671 ,1684 ,1721 ,1758 ,1767 ,1784 ,1868 ,1869 ,1876 ,1809,1829,1849,1787,1939


If you wish to send messages or make calls to Canada, you can whitelist the below prefixes also

1403, 1587, 1780, 1250, 1604, 1778, 1236, 1204, 1431, 1506, 1709, 1902, 1782, 1226, 1249, 1289, 1343, 1365, 1416, 1437, 1519, 1613, 1647, 1705, 1807, 1905, 1418, 1438, 1450, 1514, 1579, 1581, 1819, 1873, 1306, 1639, 1867


If you want to send messages or make calls to the US, US Islands, and Canada, you just need to whitelist the prefix "1"


Once you have whitelisted the above prefixes, your application should have a check such that if a message is sent to any other prefix or if calls are made to any other prefix, the API request is not triggered.


Please create a ticket with Plivo support for more details.