Following the break-up of Czechoslovakia in 1993, the successor states, the Czech Republic and Slovakia, continued to share the 42 country code until 28 February 1997, with the Czech Republic then adopting 420 and Slovakia adopting 421.^[1]

On September 22, 2002, the Czech Republic adopted a closed numbering plan, with nine-digit numbers used for local and national calls, and the dropping of the trunk code 0.

Before the change, the following arrangements would have been made for calls to Brno:

Local call:         xx xx xx xx
National call:      05/xx xx xx xx
International call: +420 5 xx xx xx xx

After the change, the dialing arrangements for calls to Brno were as follows:

Within Czech Republic:  5xx xxx xxx
Outside Czech Republic: +420 5xx xxx xxx

In the case of mobile numbers, which had to be dialed in full, the only change was that the 0 was no longer used:

Within Czech Republic:  602 xxx xxx 
Outside Czech Republic: +420 602 xxx xxx

• General emergency: 112
• Ambulance: 155
• Police: 158
• Fire brigade: 150
• Municipal police: 156
• Mountain rescue service: 1210

Other Emergency Numbers:

• Urgent gas leak: 1239
• Emergency Road Service (ABA): 1240
• Emergency Road Service (ÚAMK): 1230

O2 offers several over-the-phone information services for a fee. Note that many of the services are offered only in Czech:

• Info Line (Czech Number Directory): 1180
• Info Line (Foreign Number Directory): 1181
• Operator for changed numbers (re-numbering): 141 11
• Information on air quality: 141 10
• Exact time: 141 12
• Weather: 141 16
• Medical Information: 141 20
• Operator for international phone calls: 133 003

The first 1-3 digits (after +420) of the telephone number indicates location or network. For mobile phones, since there is number portability, the mobile phone code only indicates the original operator. For example, when a person calls a number starting with 73 (T-Mobile) but had been ported to another operator, a short voice message in Czech and English is played stating "you are calling out of a T-Mobile network" before the ringing tone. It is possible to disable this voice message.

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