EXHIBIT 11.1

ALLEGIANCE TELECOM, INC.        COMPUTATION OF PER SHARE EARNINGS (LOSS)        THREE MONTHS ENDED MARCH 31, 2002        (Dollars in thousands, except per share amounts)

|                                 |                                                     | Number
of Shares |            | Percent
Outstanding |        | Equivalent
Shares |  
|-------------------------------- | --------------------------------------------------- | ---------------- | ---------- | ------------------- | ------ | ----------------- | -
|Prior to Initial Public Offering |                                                     |                  |            |                     |        |                   |  
|                                 | 1997 Common Stock Offering                          |                  | 639        |                     | 100.00 | %                 |  
|After Initial Public Offering    |                                                     |                  |            |                     |        |                   |  
|                                 | 1998 Common Stock Offering                          |                  | 15,000,000 |                     | 100.00 | %                 |  
|                                 | Preferred Stock Converted to Common Stock           |                  | 60,511,692 |                     | 100.00 | %                 |  
|                                 | 1999 Common Stock Offering                          |                  | 21,041,100 |                     | 100.00 | %                 |  
|                                 | 2000 Common Stock Offering                          |                  | 10,703,109 |                     | 100.00 | %                 |  
|                                 | Cash in Lieu of Stock Split                         |                  | (577       | )                   | 100.00 | %                 |  
|                                 | Treasury Shares                                     |                  | (327,495   | )                   | 100.00 | %                 |  
|                                 | Warrants Exercised                                  |                  | 765,833    |                     | 100.00 | %                 |  
|                                 | Stock Options Exercised                             |                  | 1,357,725  |                     | 95.95  | %                 |  
|                                 | Employee Stock Discount Purchase Plan Shares Issued |                  | 1,359,947  |                     | 92.23  | %                 |  
|                                 | Common Stock Issued for Business Acquisitions       |                  | 5,558,747  |                     | 98.51  | %                 |  
|                                 |                                                     |                  |            |                     |        |                   |  
|                                 | WEIGHTED AVERAGE SHARES OUTSTANDING                 |                  |            |                     |        |                   |  
|                                 | NET LOSS APPLICABLE TO COMMON STOCK                 |                  |            |                     |        |                   | $
|                                 |                                                     |                  |            |                     |        |                   |  
|                                 | NET LOSS PER SHARE, BASIC AND DILUTED               |                  |            |                     |        |                   | $
|                                 |                                                     |                  |            |                     |        |                   |  

---

QuickLinks