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

Emergency calls (always toll-free)

• 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 (UAMK): 1230

Services Numbers

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

Prefixes

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.

  601 xxx xxx
  602 xxx xxx
  603 xxx xxx
  604 xxx xxx
  605 xxx xxx
  606 xxx xxx
  607 xxx xxx
  608 xxx xxx
  702 xxx xxx
  703 xxx xxx
  704 xxx xxx
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  72x xxx xxx
  730 xxx xxx
  731 xxx xxx
  732 xxx xxx
  733 xxx xxx
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  735 xxx xxx
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  737 xxx xxx
  738 xxx xxx
  739 xxx xxx
  770 xxx xxx
  771 xxx xxx
  772 xxx xxx
  773 xxx xxx
  774 xxx xxx
  775 xxx xxx
  776 xxx xxx
  778 xxx xxx
  779 xxx xxx
  790 xxx xxx
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  794 xxx xxx
  797 xxx xxx
  799 xxx xxx

References

• 117/2007 Vyhláška o číslovacích plánech sítí a služeb elektronických komunikací (in Czech)
• Horská služba - kontakty (in Czech)