Query that returns a unique ID for each different clause matched?
Schematically:
CREATE TABLE tmp ([parameters group] INT, [client_handle] CHAR(11), [mobile_no] CHAR(15));

INSERT INTO tmp VALUES
(1,'axtwe-wasst','+44 7747 122123'),
(1,'axtwe-wasst','+44 7904 223323'),
(2,'zjfft-albwq','+44 7758 444111'),
(2,'zjfft-albwq','+44 7758 444222'),
(2,'zjfft-albwq','+44 7758 444333');

SELECT DISTINCT
    [client_handle] = tmp.[parameters group],
    [user_id],
    [email],
    [mobile_no],
    [firstname],
    [surname]
FROM
    [dbo].[vAPP_UsersActive] t
JOIN 
    tmp ON t.[mobile_no] = tmp.[mobile_no];

PS. [parameters group] is not used - on shown source data it is excess, but may be useful in real task (if so then GROUP BY instead of DISTINCT must be used).