AT&T wireless subscribers in New York this morning probably cannot make or receive phone calls due to what the company calls a software upgrade.

The problem likely started at 1:30 a.m. Thursday, according to a service representative with the phone giant. Smart phones do not appear to be affected to the same degree as mobile phones.

When AT&T mobile phone users attempt to make a call, the caller likely receives a display that says the circuit or channel is not available. There is also no ring tone.

If someone tries to call the user, the call typically goes directly to voicemail.

An AT&T service representative told NBC New York that this problem appears to be restricted to phones within New York City. The representative could not offer a time frame for when the problem would be fixed.

Smart phone users apparently have texting and e-mail service, according to one subscriber. Incoming and outgoing phone calls still may not work.

(Source: NBC New York)