Method and apparatus pertaining to telephone number display formatting

1. An apparatus comprising:

a wireless transceiver;

a display;

a control circuit operably coupled to the wireless transceiver and the display and configured to:

automatically present on the display public telephony system telephone numbers using a presentation format that is standard for the public telephony system;

automatically detect attachment to a private exchange;

in response to detecting the attachment to the private exchange, and when a user inputs numbers to initiate a call, automatically switching from using the presentation format that is standard for the public telephony system and instead present on the display private-exchange telephone numbers using a presentation format that includes a non-numeric private exchange modality indicator.

2. The apparatus of claim 1 wherein the non-numeric private exchange modality indicator consists of a single alphabetic character.

3. The apparatus of claim 2 wherein the single alphabetic character is displayed contiguous with the private-exchange telephone number.

4. The apparatus of claim 3 wherein the single alphabetic character comprises the alphabetic character X.

5. The apparatus of claim 1 wherein the private exchange telephone numbers each consists of N numerals, where N is an integer selected from the group 4 and 5 .

6. The apparatus of claim 1 wherein the control circuit is configured to automatically present on the display private-exchange telephone numbers using a presentation format that includes a non-numeric private exchange modality indicator when presenting caller-identification information as corresponds to an incoming call.

7. A method comprising:

at a control circuit:

automatically presenting on a display public telephony system telephone numbers using a presentation format that is standard for the public telephony system;

automatically detect attachment to a private exchange;

in response to detecting the attachment to the private exchange, and when a user inputs numbers to initiate a call, automatically switching from using the presentation format that is standard for the public telephony system and instead presenting on the display private-exchange telephone numbers using a presentation format that includes a non-numeric private exchange modality indicator.

8. The method of claim 7 wherein the non-numeric private exchange modality indicator consists of a single alphabetic character.

9. The method of claim 8 wherein the single alphabetic character is displayed contiguous with the private-exchange telephone number.

10. The method of claim 7 wherein automatically presenting on the display private-exchange telephone numbers using a presentation format that includes a non-numeric private exchange modality indicator occurs when presenting caller-identification information as corresponds to an incoming call.

11. A non-transitory digital memory having computer instructions stored therein, which computer instructions, when executed by a processor, cause the processor to:

automatically present on a display public telephony system telephone numbers using a presentation format that is standard for the public telephony system;

automatically detect attachment to a private exchange;

in response to detecting the attachment to the private exchange, and when a user inputs numbers to initiate a call, automatically switching from using the presentation format that is standard for the public telephony system and instead present on the display private-exchange telephone numbers using a presentation format that includes a non-numeric private exchange modality indicator.

12. The non-transitory digital memory of claim 11 wherein the non-numeric private exchange modality indicator consists of a single alphabetic character.